WorldWideScience

Sample records for nanosecond rise time

  1. Generation of fast-rise time, repetitive, (sub) nanosecond, high-voltage pulses

    NARCIS (Netherlands)

    Huiskamp, T.; Pemen, A.J.M.

    2017-01-01

    In this contribution we present our fast-rise time nanosecond pulse generator, capable of generating up to 50 kV (positive and negative) rectangular pulses at a repetition rate of up to 1 kHz and with a rise time of less than 200 picoseconds. We focus on the general concepts involved in the design

  2. A nanosecond high voltage pulse device for accelerator time analytical system

    International Nuclear Information System (INIS)

    Lou Binqiao; Ding Furong; Xue Zhihua; Wang Xuemei; Shen Dingyu

    2002-01-01

    A nanosecond high voltage pulse device has been designed. The pulse rise time is 10 ns. The pulse voltage reached 16000 V. This device has been used to accelerator time analytical system, its resolution time is less than 0.8%

  3. Subnanosecond-rise-time, low-impedance pulse generator

    International Nuclear Information System (INIS)

    Druce, R.; Vogtlin, G.

    1983-01-01

    This paper describes a fast rise, low-impedance pulse generator that has been developed at the Lawrence Livermore National Laboratory. The design specifications of this generator are: 50-kV operating voltage, 1-ohm output impedance, subnanosecond rise time, and a 2 to 10 nanosecond pulse length. High repetition rate is not required. The design chosen is a parallel-plate, folded Blumlein generator. A tack switch is utilized for its simple construction and high performance. The primary diagnostic is a capacitive voltage divider with a B probe used to measure the current waveform

  4. Subnanosecond-rise-time, low-impedance pulse generator

    Energy Technology Data Exchange (ETDEWEB)

    Druce, R.; Vogtlin, G.

    1983-06-03

    This paper describes a fast rise, low-impedance pulse generator that has been developed at the Lawrence Livermore National Laboratory. The design specifications of this generator are: 50-kV operating voltage, 1-ohm output impedance, subnanosecond rise time, and a 2 to 10 nanosecond pulse length. High repetition rate is not required. The design chosen is a parallel-plate, folded Blumlein generator. A tack switch is utilized for its simple construction and high performance. The primary diagnostic is a capacitive voltage divider with a B probe used to measure the current waveform.

  5. Subnanosecond-rise-time, low-impedance pulse generator

    Science.gov (United States)

    Druce, R.; Vigtlin, G.

    1983-06-01

    A fast rise, low impedance pulse generator developed at the Lawrence Livermore National Laboratory is described. The design specifications of this generator are: 50-kV operating voltage, 1-ohm output impedance, subnanosecond rise time, and a 2 to 10 nanosecond pulse length. High repetition rate is not required. The design chosen is a parallel plate, folded Blumlein generator. A tack switch is utilized for its simple construction and high performance. The primary diagnostic is a capacitive voltage divider with a B probe used to measure the current waveform.

  6. One nanosecond pulsed electron gun systems

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1979-02-01

    At SLAC there has been a continuous need for the injection of very short bunches of electrons into the accelerator. Several time-of-flight experiments have used bursts of short pulses during a normal 1.6 micro-second rf acceleration period. Single bunch beam loading experiments made use of a short pulse injection system which included high power transverse beam chopping equipment. Until the equipment described in this paper came on line, the basic grid-controlled gun pulse was limited to a rise time of 7 nanoseconds and a pulse width of 10 nanoseconds. The system described here has a grid-controlled rise time of less than 500 pico-seconds, and a minimum pulse width of less than 1 nanosecond. Pulse burst repetition rate has been demonstrated above 20 MHz during a 1.6 microsecond rf accelerating period. The order-of-magnitude increase in gun grid switching speed comes from a new gun design which minimizes lead inductance and stray capacitance, and also increases gun grid transconductance. These gun improvements coupled with a newly designed fast pulser mounted directly within the gun envelope make possible subnanosecond pulsing of the gun

  7. Electric field measurements in a dielectric barrier nanosecond pulse discharge with sub-nanosecond time resolution

    International Nuclear Information System (INIS)

    Goldberg, Benjamin M; Shkurenkov, Ivan; Adamovich, Igor V; Lempert, Walter R; O’Byrne, Sean

    2015-01-01

    The paper presents the results of time-resolved electric field measurements in a nanosecond discharge between two plane electrodes covered by dielectric plates, using picosecond four-wave mixing diagnostics. For absolute calibration, the IR signal was measured in hydrogen at a pressure of 440 Torr, for electrostatic electric field ranging from 0 to 8 kV cm −1 . The calibration curve (i.e. the square root of IR signal intensity versus electric field) was shown to be linear. By measuring the intensities of the pump, Stokes, and IR signal beam for each laser shot during the time sweep across the high-voltage pulse, temporal evolution of the electric field in the nanosecond pulse discharge was determined with sub-nanosecond time resolution. The results are compared to kinetic modeling predictions, showing good agreement, including non-zero electric field offset before the main high voltage pulse, breakdown moment, and reduction of electric field in the plasma after breakdown. The difference between the experimental results and model predictions is likely due to non-1D structure of the discharge. Comparison with the kinetic modeling predictions shows that electric field in the nanosecond pulse discharge is controlled primarily by electron impact excitation and charge accumulation on the dielectric surfaces. (paper)

  8. High power semiconductor switching in the nanosecond regime

    International Nuclear Information System (INIS)

    Zucker, O.S.; Long, J.R.; Smith, V.L.; Page, D.J.; Roberts, J.S.

    1975-12-01

    Light activated multilayered silicon semiconductor devices have been used to switch at megawatt power levels with nanosecond turnon time. Current rate of rise of 700 kA/μs at 10 kA, with 1 kV across the load have been achieved. Recovery time of 1 millisec has been obtained. Applicability to fusion research needs is discussed

  9. Energy coupling to the plasma in repetitive nanosecond pulse discharges

    International Nuclear Information System (INIS)

    Adamovich, Igor V.; Nishihara, Munetake; Choi, Inchul; Uddi, Mruthunjaya; Lempert, Walter R.

    2009-01-01

    A new analytic quasi-one-dimensional model of energy coupling to nanosecond pulse discharge plasmas in plane-to-plane geometry has been developed. The use of a one-dimensional approach is based on images of repetitively pulsed nanosecond discharge plasmas in dry air demonstrating that the plasma remains diffuse and uniform on a nanosecond time scale over a wide range of pressures. The model provides analytic expressions for the time-dependent electric field and electron density in the plasma, electric field in the sheath, sheath boundary location, and coupled pulse energy. The analytic model predictions are in very good agreement with numerical calculations. The model demonstrates that (i) the energy coupled to the plasma during an individual nanosecond discharge pulse is controlled primarily by the capacitance of the dielectric layers and by the breakdown voltage and (ii) the pulse energy coupled to the plasma during a burst of nanosecond pulses decreases as a function of the pulse number in the burst. This occurs primarily because of plasma temperature rise and resultant reduction in breakdown voltage, such that the coupled pulse energy varies approximately proportionally to the number density. Analytic expression for coupled pulse energy scaling has been incorporated into the air plasma chemistry model, validated previously by comparing with atomic oxygen number density measurements in nanosecond pulse discharges. The results of kinetic modeling using the modified air plasma chemistry model are compared with time-resolved temperature measurements in a repetitively pulsed nanosecond discharge in air, by emission spectroscopy, and purely rotational coherent anti-Stokes Raman spectroscopy showing good agreement.

  10. Quad nanosecond delay module

    International Nuclear Information System (INIS)

    McDonald, R.J.; Hunter, J.B.; Wozniak, G.J.

    1986-04-01

    Four nanosecond (ns) delay units have been designed to fit in a single-width NIM module. This module is particularly suited for use in conjunction with quad constant fraction timing discriminators (CFTDs) since it has four delay units that can be placed adjacent to the four units of the CFTD. A series of different length cables connected via DIP toggle switches provide delays of 0.60 ns in 4 ns increments. Thus, the CFTD delay can be optimized for pulses of different rise times from approx.10-100 ns. Design work for the PC board and silkscreening of the front panel were done with the MacDraw program on the Apple Mackintosh computer and printed with the Lasewriter printer. 6 refs

  11. Sub-nanosecond time-of-flight for segmented silicon detectors

    International Nuclear Information System (INIS)

    Souza, R.T. de; Alexander, A.; Brown, K.; Floyd, B.; Gosser, Z.Q.; Hudan, S.; Poehlman, J.; Rudolph, M.J.

    2011-01-01

    Development of a multichannel time-of-flight system for readout of a segmented, ion-passivated, ion-implanted silicon detector is described. This system provides sub-nanosecond resolution (δt∼370ps) even for low energy α particles which deposit E≤7.687MeV in the detector.

  12. X-ray emission from a nanosecond-pulse discharge in an inhomogeneous electric field at atmospheric pressure

    International Nuclear Information System (INIS)

    Zhang Cheng; Shao Tao; Ren Chengyan; Zhang Dongdong; Tarasenko, Victor; Kostyrya, Igor D.; Ma Hao; Yan Ping

    2012-01-01

    This paper describes experimental studies of the dependence of the X-ray intensity on the anode material in nanosecond high-voltage discharges. The discharges were generated by two nanosecond-pulse generators in atmospheric air with a highly inhomogeneous electric field by a tube-plate gap. The output pulse of the first generator (repetitive pulse generator) has a rise time of about 15 ns and a full width at half maximum of 30–40 ns. The output of the second generator (single pulse generator) has a rise time of about 0.3 ns and a full width at half maximum of 1 ns. The electrical characteristics and the X-ray emission of nanosecond-pulse discharge in atmospheric air are studied by the measurement of voltage-current waveforms, discharge images, X-ray count and dose. Our experimental results showed that the anode material rarely affects electrical characteristics, but it can significantly affect the X-ray density. Comparing the density of X-rays, it was shown that the highest x-rays density occurred in the diffuse discharge in repetitive pulse mode, then the spark discharge with a small air gap, and then the corona discharge with a large air gap, in which the X-ray density was the lowest. Therefore, it could be confirmed that the bremsstrahlung at the anode contributes to the X-ray emission from nanosecond-pulse discharges.

  13. Numerical simulation of nanosecond-pulse electrical discharges

    Science.gov (United States)

    Poggie, J.; Adamovich, I.; Bisek, N.; Nishihara, M.

    2013-02-01

    Recent experiments with a nanosecond-pulse, dielectric barrier discharge at the stagnation point of a Mach 5 cylinder flow have demonstrated the formation of weak shock waves near the electrode edge, which propagate upstream and perturb the bow shock. This is a promising means of flow control, and understanding the detailed physics of the conversion of electrical energy into gas motion will aid in the design of efficient actuators based on the concept. In this work, a simplified configuration with planar symmetry was chosen as a vehicle to develop a physics-based model of nanosecond-pulse discharges, including realistic air kinetics, electron energy transport, and compressible bulk gas flow. A reduced plasma kinetic model (23 species and 50 processes) was developed to capture the dominant species and reactions for energy storage and thermalization in the discharge. The kinetic model included electronically and vibrationally excited species, and several species of ions and ground state neutrals. The governing equations included the Poisson equation for the electric potential, diffusion equations for each neutral species, conservation equations for each charged species, and mass-averaged conservation equations for the bulk gas flow. The results of calculations with this model highlighted the path of energy transfer in the discharge. At breakdown, the input electrical energy was transformed over a time scale on the order of 1 ns into chemical energy of ions, dissociation products, and vibrationally and electronically excited particles. About 30% of this energy was subsequently thermalized over a time scale of 10 µs. Since the thermalization time scale was faster than the acoustic time scale, the heat release led to the formation of weak shock waves originating near the sheath edge, consistent with experimental observations. The computed translational temperature rise (40 K) and nitrogen vibrational temperature rise (370 K) were of the same order of magnitude as

  14. Nanosecond-level time synchronization of AERA using a beacon reference transmitter and commercial airplanes

    Science.gov (United States)

    Huege, Tim

    2017-03-01

    Radio detection of cosmic-ray air showers requires time synchronization of detectors on a nanosecond level, especially for advanced reconstruction algorithms based on the wavefront curvature and for interferometric analysis approaches. At the Auger Engineering Radio Array, the distributed, autonomous detector stations are time-synchronized via the Global Positioning System which, however, does not provide sufficient timing accuracy. We thus employ a dedicated beacon reference transmitter to correct for eventby-event clock drifts in our offline data analysis. In an independent cross-check of this "beacon correction" using radio pulses emitted by commercial airplanes, we have shown that the combined timing accuracy of the two methods is better than 2 nanoseconds.

  15. Abnormal polarity effect in nanosecond-pulse breakdown of SF6 and nitrogen

    International Nuclear Information System (INIS)

    Shao, Tao; Tarasenko, Victor F.; Zhang, Cheng; Beloplotov, Dmitry S.; Yang, Wenjin; Lomaev, Mikhail I.; Zhou, Zhongsheng; Sorokin, Dmitry A.; Yan, Ping

    2014-01-01

    The breakdown of gas gaps in an inhomogeneous electric field at subnanosecond and nanosecond voltage pulse rise times are studied, and the famous polarity effect in point-to-plane gaps is investigated. It is shown that at a voltage pulse rise time of ∼0.5 ns, the inversion of polarity effect takes place not only in electronegative gases such as SF 6 , but also occurs in electropositive nitrogen. The inversion of polarity effect is related to a delay of electron emission from the plane cathode on arrival of the ionization wave front anode to the cathode. It is found that with a voltage pulse rise time of ∼0.5 ns, the inversion of polarity effect occurs at SF 6 and SF 6 –N 2 pressures of 0.25 MPa and lower, and with a voltage pulse rise time of 15 ns, at a SF 6 pressure lower than 0.12 MPa.

  16. Nanosecond-level time synchronization of AERA using a beacon reference transmitter and commercial airplanes

    Directory of Open Access Journals (Sweden)

    Huege Tim

    2017-01-01

    Full Text Available Radio detection of cosmic-ray air showers requires time synchronization of detectors on a nanosecond level, especially for advanced reconstruction algorithms based on the wavefront curvature and for interferometric analysis approaches. At the Auger Engineering Radio Array, the distributed, autonomous detector stations are time-synchronized via the Global Positioning System which, however, does not provide sufficient timing accuracy. We thus employ a dedicated beacon reference transmitter to correct for eventby-event clock drifts in our offline data analysis. In an independent cross-check of this “beacon correction” using radio pulses emitted by commercial airplanes, we have shown that the combined timing accuracy of the two methods is better than 2 nanoseconds.

  17. Radial Distribution of the Nanosecond Dielectric Barrier Discharge Current in Atmospheric-Pressure Air

    Science.gov (United States)

    Malashin, M. V.; Moshkunov, S. I.; Khomich, V. Yu.; Shershunova, E. A.

    2018-01-01

    Experimental results on the radial distribution of the nanosecond dielectric barrier discharge (DBD) current in flat millimeter air gaps under atmospheric pressure and natural humidity of 40-60% at a voltage rise rate at the electrodes of 250 V/ns are presented. The time delay of the appearance of discharge currents was observed to increase from the center to the periphery of the air gap at discharge gap heights above 3 mm, which correlated with the appearance of constricted channels against the background of the volume DBD plasma. Based on the criterion of the avalanche-streamer transition, it is found out that the development of a nanosecond DBD in air gaps of 1-3 mm occurs by the streamer mechanism.

  18. A comparison between characteristics of atmospheric-pressure plasma jets sustained by nanosecond- and microsecond-pulse generators in helium

    International Nuclear Information System (INIS)

    Zhang, Cheng; Shao, Tao; Wang, Ruixue; Yan, Ping; Zhou, Zhongsheng; Zhou, Yixiao

    2014-01-01

    Power source is an important parameter that can affect the characteristics of atmospheric-pressure plasma jets (APPJs), because it can play a key role on the discharge characteristics and ionization process of APPJs. In this paper, the characteristics of helium APPJs sustained by both nanosecond-pulse and microsecond-pulse generators are compared from the aspects of plume length, discharge current, consumption power, energy, and optical emission spectrum. Experimental results showed that the pulsed APPJ was initiated near the high-voltage electrode with a small curvature radius, and then the stable helium APPJ could be observed when the applied voltage increased. Moreover, the discharge current of the nanosecond-pulse APPJ was larger than that of the microsecond-pulse APPJ. Furthermore, although the nanosecond-pulse generator consumed less energy than the microsecond-pulse generator, longer plume length, larger instantaneous power per pulse and stronger spectral line intensity could be obtained in the nanosecond-pulse excitation case. In addition, some discussion indicated that the rise time of the applied voltage could play a prominent role on the generation of APPJs

  19. A CMOS delay locked loop and sub-nanosecond time-to-digital converter chip

    International Nuclear Information System (INIS)

    Santos, D.M.; Dow, S.F.; Flasck, J.M.; Levi, M.E.

    1996-01-01

    Phase-locked loops have been employed in the past to obtain sub-nanosecond time resolution in high energy physics and nuclear science applications. An alternative solution based on a delay-locked loop (DLL) is described. This solution allows for a very high level of integration yet still offers resolution in the sub-nanosecond regime. Two variations on this solution are outlined. A novel phase detector, based on the Mueller C-element, is used to implement a charge pump where the injected charge approaches zero as the loop approaches lock on the leading edge of an input clock reference. This greatly reduces timing jitter. In the second variation the loop locks to both the leading and trailing clock edges. In this second implementation, software coded layout generators are used to automatically layout a highly integrated, multichannel, time-to-digital converter (TDC) targeted for one specific frequency. The two circuits, DLL and TDC, are implemented in CMOS 1.2 microm and 0.8 microm technologies, respectively. Test results show a timing jitter of less than 30 ps for the DLL circuit and less than 190 ps integral and differential nonlinearity for the TDC circuit

  20. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field.

    Science.gov (United States)

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-06-25

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge.

  1. A CMOS delay locked loop and sub-nanosecond time-to-digital converter chip

    International Nuclear Information System (INIS)

    Santos, D.M.; Dow, S.F.; Levi, M.E.

    1995-12-01

    Many high energy physics and nuclear science applications require sub-nanosecond time resolution measurements over many thousands of detector channels. Phase-locked loops have been employed in the past to obtain accurate time references for these measurements. An alternative solution, based on a delay-locked loop (DLL) is described. This solution allows for a very high level of integration yet still offers resolution in the sub-nanosecond regime. Two variations on this solution are outlined. A novel phase detector, based on the Muller C element, is used to implement a charge pump where the injected charge approaches zero as the loop approaches lock on the leading edge of an input clock reference. This greatly reduces timing jitter. In the second variation the loop locks to both the leading and trailing clock edges. In this second implementation, software coded layout generators are used to automatically layout a highly integrated, multi-channel, time to digital converter (TDC). Complex clock generation can be, achieved by taking symmetric taps off the delay elements. The two circuits, DLL and TDC, were implemented in a CMOS 1.2μm and 0.8μm technology, respectively. Test results show a timing jitter of less than 35 ps for the DLL circuit and better solution for the TDC circuit

  2. Time-domain calculation of sub-nanosecond pulse launched by a proton beam

    International Nuclear Information System (INIS)

    Chan, Kwok-Chi Dominic; Cooper, R.K.

    1990-01-01

    Using the finite-difference time-domain code TBCI, we have numerically calculated the radiation from a sub-nanosecond 800-MeV proton bunch as it is launched into space. The calculation is compared to measurements of the time history of the radiated fields and good agreement is found. A movie showing the development of the radiation pattern will be shown during the presentation at this conference, namely, the First Los Alamos Symposium on Ultra-Wideband Radar. 6 refs., 7 figs

  3. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field

    Science.gov (United States)

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-01-01

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge. PMID:25071294

  4. Nanosecond bipolar pulse generators for bioelectrics.

    Science.gov (United States)

    Xiao, Shu; Zhou, Chunrong; Yang, Enbo; Rajulapati, Sambasiva R

    2018-04-26

    Biological effects caused by a nanosecond pulse, such as cell membrane permeabilization, peripheral nerve excitation and cell blebbing, can be reduced or cancelled by applying another pulse of reversed polarity. Depending on the degree of cancellation, the pulse interval of these two pulses can be as long as dozens of microseconds. The cancellation effect diminishes as the pulse duration increases. To study the cancellation effect and potentially utilize it in electrotherapy, nanosecond bipolar pulse generators must be made available. An overview of the generators is given in this paper. A pulse forming line (PFL) that is matched at one end and shorted at the other end allows a bipolar pulse to be produced, but no delay can be inserted between the phases. Another generator employs a combination of a resistor, an inductor and a capacitor to form an RLC resonant circuit so that a bipolar pulse with a decaying magnitude can be generated. A third generator is a converter, which converts an existing unipolar pulse to a bipolar pulse. This is done by inserting an inductor in a transmission line. The first phase of the bipolar pulse is provided by the unipolar pulse's rising phase. The second phase is formed during the fall time of the unipolar pulse, when the inductor, which was previously charged during the flat part of the unipolar pulse, discharges its current to the load. The fourth type of generator uses multiple MOSFET switches stacked to turn on a pre-charged, bipolar RC network. This approach is the most flexible in that it can generate multiphasic pulses that have different amplitudes, delays, and durations. However, it may not be suitable for producing short nanosecond pulses (<100 ns), whereas the PFL approach and the RLC approach with gas switches are used for this range. Thus, each generator has its own advantages and applicable range. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric fields

    International Nuclear Information System (INIS)

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-01-01

    In this study, we report experimental results on fast intensified charge-coupled device (ICCD) imaging of the development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of the electric field in the discharge. The uniformity of the discharge images obtained with nanosecond exposure times was analysed using chi-square test. The results indicate that DBD uniformity strongly depends on the applied (global) electric field in the discharge gap, which is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is a transition from filamentary to uniform DBD mode that correlates to the corresponding decrease of the maximum local electric field in the discharge. (fast track communication)

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

    Science.gov (United States)

    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.

  7. Development of an electron momentum spectrometer for time-resolved experiments employing nanosecond pulsed electron beam

    Science.gov (United States)

    Tang, Yaguo; Shan, Xu; Liu, Zhaohui; Niu, Shanshan; Wang, Enliang; Chen, Xiangjun

    2018-03-01

    The low count rate of (e, 2e) electron momentum spectroscopy (EMS) has long been a major limitation of its application to the investigation of molecular dynamics. Here we report a new EMS apparatus developed for time-resolved experiments in the nanosecond time scale, in which a double toroidal energy analyzer is utilized to improve the sensitivity of the spectrometer and a nanosecond pulsed electron gun with a repetition rate of 10 kHz is used to obtain an average beam current up to nA. Meanwhile, a picosecond ultraviolet laser with a repetition rate of 5 kHz is introduced to pump the sample target. The time zero is determined by photoionizing the target using a pump laser and monitoring the change of the electron beam current with time delay between the laser pulse and electron pulse, which is influenced by the plasma induced by the photoionization. The performance of the spectrometer is demonstrated by the EMS measurement on argon using a pulsed electron beam, illustrating the potential abilities of the apparatus for investigating the molecular dynamics in excited states when employing the pump-probe scheme.

  8. A Novel Nanosecond Pulsed Power Unit for the Formation of ·OH in Water

    Science.gov (United States)

    Li, Shengli; Hu, Sheng; Zhang, Han

    2012-04-01

    A novel nanosecond pulsed power unit was developed for plasma treatment of wastewater, based on the theory of magnetic pulse compression and semiconductor opening switch (SOS). The peak value, rise time and pulse duration of the output voltage were observed to be -51 kV, 60 ns and 120 ns, respectively. The concentrations of ·OH generated by the novel nanosecond pulsed plasma power were determined using the method of high-performance liquid chromatography (HPLC). The results showed that the concentrations of ·OH increased with the increase in peak voltage, and the generation rates of ·OH were 4.1 × 10-10 mol/s, 5.7 × 10-10 mol/s, and 7.7 × 10-10 mol/s at 30 kV, 35 kV, and 40 kV, respectively. The efficiency of OH generation was found to be independent of the input parameters for applied power, with an average value of 3.23×10-12 mol/J obtained.

  9. A Novel Nanosecond Pulsed Power Unit for the Formation of ·OH in Water

    International Nuclear Information System (INIS)

    Li Shengli; Hu Sheng; Zhang Han

    2012-01-01

    A novel nanosecond pulsed power unit was developed for plasma treatment of wastewater, based on the theory of magnetic pulse compression and semiconductor opening switch (SOS). The peak value, rise time and pulse duration of the output voltage were observed to be -51 kV, 60 ns and 120 ns, respectively. The concentrations of ·OH generated by the novel nanosecond pulsed plasma power were determined using the method of high-performance liquid chromatography (HPLC). The results showed that the concentrations of ·OH increased with the increase in peak voltage, and the generation rates of ·OH were 4.1 × 10 -10 mol/s, 5.7 × 10 -10 mol/s, and 7.7 × 10 -10 mol/s at 30 kV, 35 kV, and 40 kV, respectively. The efficiency of OH generation was found to be independent of the input parameters for applied power, with an average value of 3.23×10 -12 mol/J obtained. (plasma technology)

  10. The effect of polymer type on electric breakdown strength on a nanosecond time scale

    Institute of Scientific and Technical Information of China (English)

    Zhao Liang; Su Jian-Cang; Pan Ya-Feng; Zhang Xi-Bo

    2012-01-01

    Based on the concepts of fast polarization,effective electric field and electron impact ionization criterion,the effect of polymer type on electric breakdown strength (EBD) on a nanosecond time scale is investigated,and a formula that qualitatively characterizes the relation between the electric breakdown strength and the polymer type is derived.According to this formula,it is found that the electric breakdown strength decreases with an increase in the effective relative dielectric constants of the polymers.By calculating the effective relative dielectric constants for different types of polymers,the theoretical relation for the electric breakdown strengths of common polymers is predicted.To verify the prediction,the polymers of PE (polyethylene),PTFE (polytetrafluoroethelene),PMMA (organic glass) and Nylon are tested with a nanosecond-pulse generator.The experimental result shows EBD (PTFE) > EBD (PMMA) > EBD (Nylon) > EBD (PE).This result is consistent with the theoretical prediction.

  11. Transient Features in Nanosecond Pulsed Electric Fields Differentially Modulate Mitochondria and Viability

    Science.gov (United States)

    Beebe, Stephen J.; Chen, Yeong-Jer; Sain, Nova M.; Schoenbach, Karl H.; Xiao, Shu

    2012-01-01

    It is hypothesized that high frequency components of nanosecond pulsed electric fields (nsPEFs), determined by transient pulse features, are important for maximizing electric field interactions with intracellular structures. For monopolar square wave pulses, these transient features are determined by the rapid rise and fall of the pulsed electric fields. To determine effects on mitochondria membranes and plasma membranes, N1-S1 hepatocellular carcinoma cells were exposed to single 600 ns pulses with varying electric fields (0–80 kV/cm) and short (15 ns) or long (150 ns) rise and fall times. Plasma membrane effects were evaluated using Fluo-4 to determine calcium influx, the only measurable source of increases in intracellular calcium. Mitochondria membrane effects were evaluated using tetramethylrhodamine ethyl ester (TMRE) to determine mitochondria membrane potentials (ΔΨm). Single pulses with short rise and fall times caused electric field-dependent increases in calcium influx, dissipation of ΔΨm and cell death. Pulses with long rise and fall times exhibited electric field-dependent increases in calcium influx, but diminished effects on dissipation of ΔΨm and viability. Results indicate that high frequency components have significant differential impact on mitochondria membranes, which determines cell death, but lesser variances on plasma membranes, which allows calcium influxes, a primary determinant for dissipation of ΔΨm and cell death. PMID:23284682

  12. Review of supershort avalanche electron beam during nanosecond-pulse discharges in some gases

    Directory of Open Access Journals (Sweden)

    Victor F. Tarasenko

    2017-05-01

    Full Text Available Supershort avalanche electron beam (SAEB plays an important role in nanosecond-pulse discharges. This paper aims at reviewing experiments results on characteritics of SAEB and its spectra in different gases in nanosecond-pulse discharges. All the joint experiments were carried in the Institute of High Current Electronics of the Russian Academy of Sciences and the Institute of Electrical Engineering of the Chinese Academy of Sciences. In these experiments, the generation of a SAEB in SF6 in an inhomogeneous electric field was studied on three generators with pulse rise times of 0.3, 0.5 and ∼2 ns. Firstly, the comparison of SAEB parameters in SF6 with those obtained in other gases (air, nitrogen, argon, and krypton is introduced. Secondly, the SAEB spectra in SF6 and air at pressures of 10 kPa (75 torr, and 0.1 MPa (750 torr are reviewed and discussed. Finally, 1.5-D theoretical simulation of the supershort pulse of the fast electron beam in a coaxial diode filled with SF6 at atmospheric pressure is described. The simulation was carried out in the framework of hybrid model for discharge and runaway electron kinetics. The above research progress can provide better understanding of the investigation into the mechanism of nanosecond-pulse discharges.

  13. Temporally resolved imaging on quenching and re-ignition of nanosecond underwater discharge

    Directory of Open Access Journals (Sweden)

    Yong Yang

    2012-12-01

    Full Text Available This paper presents the temporally resolved images of plasma discharge in de-ionized water. The discharge was produced by high voltage pulses with 0.3 ns rise time and 10 ns duration. The temporal resolution of the imaging system was one nanosecond. A unique three-stage process, including a fast ignition at the leading edge of the pulse, quenching at the plateau of the pulse, and self re-ignition at the trailing edge of the pulse, was observed in a single pulse cycle. The maximum measured propagation velocity of the plasma discharge was about 1000 km/s. The possibility of direct ionization in water under high reduced electric field conditions was discussed.

  14. Nanosecond neutron generator

    International Nuclear Information System (INIS)

    Lobov, S.I.; Pavlovskaya, N.G.; Pukhov, S.P.

    1991-01-01

    High-voltage nanosecond neutron generator for obtaining neutrons in D-T reaction is described. Yield of 6x10 6 neutron/pulse was generated in a sealed gas-filled diode with a target on the cathode by accelerating pulse voltage of approximately 0.5 MV and length at half-height of 0.5 ns and deuterium pressure of 6x10 -2 Torr. Ways of increasing neutron yield and possibilities of creating generators of nanosecond neutron pulses with great service life are considered

  15. Compton suppression through rise-time analysis

    International Nuclear Information System (INIS)

    Selvi, S.; Celiktas, C.

    2007-01-01

    We studied Compton suppression for 60 Co and 137 Cs radioisotopes using a signal selection criterion based on contrasting the fall time of the signals composing the photo peak with those composing the Compton continuum. The fall time criterion is employed by using the pulse shape analysis observing the change in the fall times of the gamma-ray pulses. This change is determined by measuring the changes in the rise times related to the fall time of the scintillator and the timing signals related to the fall time of the input signals. We showed that Compton continuum suppression is achieved best via the precise timing adjustment of an analog rise-time analyzer connected to a NaI(Tl) scintillation spectrometer

  16. Time-resolved dynamics of nanosecond laser-induced phase explosion

    International Nuclear Information System (INIS)

    Porneala, Cristian; Willis, David A

    2009-01-01

    Visualization of Nd : YAG laser ablation of aluminium targets was performed by a shadowgraph apparatus capable of imaging the dynamics of ablation with nanosecond time resolution. Direct observations of vaporization, explosive phase change and shock waves were obtained. The influence of vaporization and phase explosion on shock wave velocity was directly measured. A significant increase in the shock wave velocity was observed at the onset of phase explosion. However, the shock wave behaviour followed the form of a Taylor-Sedov spherical shock below and above the explosive phase change threshold. The jump in the shock wave velocity above phase explosion threshold is attributed to the release of stored enthalpy in the superheated liquid surface. The energy released during phase explosion was estimated by fitting the transient shock wave position to the Taylor scaling rules. Results of temperature calculations indicate that the vapour temperature at the phase explosion threshold is slightly higher than the critical temperature at the early stages of the shock wave formation. The shock wave pressure nearly doubled when transitioning from normal vaporization to phase explosion.

  17. Spectroscopic studies of model photo-receptors: validation of a nanosecond time-resolved micro-spectrophotometer design using photoactive yellow protein and α-phycoerythrocyanin.

    Science.gov (United States)

    Purwar, Namrta; Tenboer, Jason; Tripathi, Shailesh; Schmidt, Marius

    2013-09-13

    Time-resolved spectroscopic experiments have been performed with protein in solution and in crystalline form using a newly designed microspectrophotometer. The time-resolution of these experiments can be as good as two nanoseconds (ns), which is the minimal response time of the image intensifier used. With the current setup, the effective time-resolution is about seven ns, determined mainly by the pulse duration of the nanosecond laser. The amount of protein required is small, on the order of 100 nanograms. Bleaching, which is an undesirable effect common to photoreceptor proteins, is minimized by using a millisecond shutter to avoid extensive exposure to the probing light. We investigate two model photoreceptors, photoactive yellow protein (PYP), and α-phycoerythrocyanin (α-PEC), on different time scales and at different temperatures. Relaxation times obtained from kinetic time-series of difference absorption spectra collected from PYP are consistent with previous results. The comparison with these results validates the capability of this spectrophotometer to deliver high quality time-resolved absorption spectra.

  18. Design and implementation of a nanosecond time-stamping readout system-on-chip for photo-detectors

    International Nuclear Information System (INIS)

    Anvar, Shebli; Château, Frédéric; Le Provost, Hervé; Louis, Frédéric; Manolopoulos, Konstantinos; Moudden, Yassir; Vallage, Bertrand; Zonca, Eric

    2014-01-01

    A readout system suitable for a large number of synchronized photo-detection units has been designed. Each unit embeds a specifically designed fully integrated communicating system based on Xilinx FPGA SoC technology. It runs the VxWorks real-time OS and a custom data acquisition software designed within the Ice middleware framework, resulting in a highly flexible, controllable and scalable distributed application. Clock distribution and delay calibration over customized fixed latency gigabit Ethernet links enable synchronous time-stamping of events with nanosecond precision. The implementation of this readout system on several data-collecting units as well as its performances are described

  19. Nanosecond barrier discharge in a krypton/helium mixture containing mercury dibromide: Optical emission and plasma parameters

    Science.gov (United States)

    Malinina, A. A.; Starikovskaya, S. M.; Malinin, A. N.

    2015-01-01

    Spectral and electrical characteristics of atmospheric-pressure nanosecond barrier discharge plasma in a HgBr2/Kr/He mixture have been investigated. The discharge was initiated by positive 10-kV voltage pulses with a rise time of 4 ns and a half-amplitude duration of 28 ns. Emission from exciplex HgBr ( B 2Σ{1/2/+} - X 2Σ{1/2/+}) and KrBr ( B 2Σ{1/2/+} - X 2Σ{1/2/+}, C3/2-AΠ1/2, D1/2-AΠ1/2) molecules have been studied. From the time evolution of the B-X transition spectra of the HgBr molecule (502 nm) and KrBr molecule (207 nm), a mechanism of the formation of the exciplex molecules in the nanosecond discharge has been deduced. The distributions of the energies and rates of the processes responsible for emission from HgBr and KrBr molecules have been analyzed by numerically solving the Boltzmann equation for the electron distribution function. Experiments have confirmed the possibility of optimizing the voltage supply pulse for maximizing the efficiency of simultaneous emission in the UV and visible (green) spectral ranges from atmospheric-pressure discharge in the HgBr2/Kr/He mixture.

  20. From RISING to the DESPEC fast-timing project within NUSTAR at FAIR: Sub-nanosecond nuclear timing spectroscopy with LaBr3 scintillators

    International Nuclear Information System (INIS)

    Regan, P.H.

    2012-01-01

    This paper summarises a presentation given at the IRRMA8 conference in June 2011 which reviewed briefly the topic of current research studies in the evolution of nuclear structure with changing proton and neutron numbers. A short review of relevant contemporary spectroscopic studies of the structure of nuclei with highly exotic N/Z ratios using projectile fragmentation and fission reactions is given, together with an overview of some of the physics research aims to be attacked using the proposed Decay Spectroscopy (DESPEC) LaBr 3 Fast-Timing gamma-ray array for the NUSTAR project at the upcoming Facility for Anti-Proton and Ion Research (FAIR). Examples of recent results using both ‘isomer’ and β − -delayed gamma-ray decay measurements with the Stopped RISING hyper-pure germanium array at GSI are summarised and used to highlight some of the fundamental physics studies which are expected to become available in this area of research in the coming decade. Examples of the performance of cerium-doped LaBr 3 detectors from ‘in-beam’ test experiments are presented together with initial plans for the geometry of the planned multi-detector LaBr 3 (Ce) array for DESPEC. - Highlights: ► The paper presents an overview of nuclear excitation systematics in even–even nuclei. ► The paper gives a description of the Stopped RISING gamma-ray spectrometer. ► This paper gives some of the recent scientific results in nuclear spectroscopy of exotic nuclei. ► The paper shows the use of halide scintillation detectors for gamma-ray decay studies of nuclei. ► This paper shows the use of LaBr 3 detectors to nuclear excited state lifetimes in the ns regime.

  1. Interconnect rise time in superconducting integrating circuits

    International Nuclear Information System (INIS)

    Preis, D.; Shlager, K.

    1988-01-01

    The influence of resistive losses on the voltage rise time of an integrated-circuit interconnection is reported. A distribution-circuit model is used to present the interconnect. Numerous parametric curves are presented based on numerical evaluation of the exact analytical expression for the model's transient response. For the superconducting case in which the series resistance of the interconnect approaches zero, the step-response rise time is longer but signal strength increases significantly

  2. Nanosecond X-ray detector based on high resistivity ZnO single crystal semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaolong; He, Yongning, E-mail: yongning@mail.xjtu.edu.cn; Peng, Wenbo; Huang, Zhiyong; Qi, Xiaomeng; Pan, Zijian; Zhang, Wenting [School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Chen, Liang; Liu, Jinliang; Zhang, Zhongbing; Ouyang, Xiaoping [Radiation Detection Research Center, Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

    2016-04-25

    The pulse radiation detectors are sorely needed in the fields of nuclear reaction monitoring, material analysis, astronomy study, spacecraft navigation, and space communication. In this work, we demonstrate a nanosecond X-ray detector based on ZnO single crystal semiconductor, which emerges as a promising compound-semiconductor radiation detection material for its high radiation tolerance and advanced large-size bulk crystal growth technique. The resistivity of the ZnO single crystal is as high as 10{sup 13} Ω cm due to the compensation of the donor defects (V{sub O}) and acceptor defects (V{sub Zn} and O{sub i}) after high temperature annealing in oxygen. The photoconductive X-ray detector was fabricated using the high resistivity ZnO single crystal. The rise time and fall time of the detector to a 10 ps pulse electron beam are 0.8 ns and 3.3 ns, respectively, indicating great potential for ultrafast X-ray detection applications.

  3. Nanosecond fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Leskovar, B.

    1985-03-01

    This article is a summary of a short course lecture given in conjunction with the 1984 Nuclear Science Symposium. Measuring systems for nanosecond fluorescence spectroscopy using single-photon counting techniques are presented. These involve systems based on relaxation-type spark gap light pulser and synchronously pumped mode-locked dye lasers. Furthermore, typical characteristics and optimization of operating conditions of the critical components responsible for the system time resolution are discussed. A short comparison of the most important deconvolution methods for numerical analysis of experimental data is given particularly with respect to the signal-to-noise ratio of the fluorescence signal. 22 refs., 8 figs

  4. Histopathology of normal skin and melanomas after nanosecond pulsed electric field treatment

    Science.gov (United States)

    Chen, Xinhua; Swanson, R. James; Kolb, Juergen F.; Nuccitelli, Richard; Schoenbach, Karl H.

    2011-01-01

    Nanosecond pulsed electric fields (nsPEFs) can affect the intracellular structures of cells in vitro. This study shows the direct effects of nsPEFs on tumor growth, tumor volume, and histological characteristics of normal skin and B16-F10 melanoma in SKH-1 mice. A melanoma model was set up by injecting B16-F10 into female SKH-1 mice. After a 100-pulse treatment with an nsPEF (40-kV/cm field strength; 300-ns duration; 30-ns rise time; 2-Hz repetition rate), tumor growth and histology were studied using transillumination, light microscopy with hematoxylin and eosin stain and transmission electron microscopy. Melanin and iron within the melanoma tumor were also detected with specific stains. After nsPEF treatment, tumor development was inhibited with decreased volumes post-nsPEF treatment compared with control tumors (Pelectric fields surrounding the needle electrodes. PMID:19730404

  5. Low charge state heavy ion production with sub-nanosecond laser.

    Science.gov (United States)

    Kanesue, T; Kumaki, M; Ikeda, S; Okamura, M

    2016-02-01

    We have investigated laser ablation plasma of various species using nanosecond and sub-nanosecond lasers for both high and low charge state ion productions. We found that with sub-nanosecond laser, the generated plasma has a long tail which has low charge state ions determined by an electrostatic ion analyzer even under the laser irradiation condition for highly charged ion production. This can be caused by insufficient laser absorption in plasma plume. This property might be suitable for low charge state ion production. We used a nanosecond laser and a sub-nanosecond laser for low charge state ion production to investigate the difference of generated plasma using the Zirconium target.

  6. Low charge state heavy ion production with sub-nanosecond laser

    Energy Technology Data Exchange (ETDEWEB)

    Kanesue, T., E-mail: tkanesue@bnl.gov; Okamura, M. [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Kumaki, M. [Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Nishina Center for Accelerator-Based Science, RIKEN, Saitama 351-0198 (Japan); Ikeda, S. [Nishina Center for Accelerator-Based Science, RIKEN, Saitama 351-0198 (Japan); Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Kanagawa 226-8503 (Japan)

    2016-02-15

    We have investigated laser ablation plasma of various species using nanosecond and sub-nanosecond lasers for both high and low charge state ion productions. We found that with sub-nanosecond laser, the generated plasma has a long tail which has low charge state ions determined by an electrostatic ion analyzer even under the laser irradiation condition for highly charged ion production. This can be caused by insufficient laser absorption in plasma plume. This property might be suitable for low charge state ion production. We used a nanosecond laser and a sub-nanosecond laser for low charge state ion production to investigate the difference of generated plasma using the Zirconium target.

  7. Gas Discharge Produced by Strong Microwaves of Nanosecond Duration

    International Nuclear Information System (INIS)

    Vikharev, A.L.

    2000-01-01

    The results of the investigation of nanosecond microwave discharge are reviewed. Nanosecond microwave discharge is a new branch of gas discharge physics. The paper lists base types of microwave generators used to produce nanosecond discharge and classifies the discharges relative to their base parameters: the way the discharge gets localized in a limited space, amplitude and frequency of microwave field, gas pressure, duration of microwave pulses. The laboratory experiments performed and the new effects which appear in nanosecond microwave discharge are briefly summarized. Different applications of such a discharge are analyzed on the basis of the experimental modelling. (author)

  8. Method of the nanosecond microstructure creation of the negative ion beam

    International Nuclear Information System (INIS)

    Novikov-Borodin, A.V.

    2001-01-01

    The method of the nanosecond microstructure creation of the negative ion beam with nanosecond edge times is presented. The method of creation does not destroy the beam compensation by the residual gas,so it available for low-energy beams. Such effects as a beam divergence and,therefore,a bad beam transport are overcome. The two plate travelling wave chopper is used.The special shape of the plate deflecting voltage is needed. The estimations and a comparison with the existing methods of a beam deflection are presented

  9. Transmembrane molecular transport during versus after extremely large, nanosecond electric pulses.

    Science.gov (United States)

    Smith, Kyle C; Weaver, James C

    2011-08-19

    Recently there has been intense and growing interest in the non-thermal biological effects of nanosecond electric pulses, particularly apoptosis induction. These effects have been hypothesized to result from the widespread creation of small, lipidic pores in the plasma and organelle membranes of cells (supra-electroporation) and, more specifically, ionic and molecular transport through these pores. Here we show that transport occurs overwhelmingly after pulsing. First, we show that the electrical drift distance for typical charged solutes during nanosecond pulses (up to 100 ns), even those with very large magnitudes (up to 10 MV/m), ranges from only a fraction of the membrane thickness (5 nm) to several membrane thicknesses. This is much smaller than the diameter of a typical cell (∼16 μm), which implies that molecular drift transport during nanosecond pulses is necessarily minimal. This implication is not dependent on assumptions about pore density or the molecular flux through pores. Second, we show that molecular transport resulting from post-pulse diffusion through minimum-size pores is orders of magnitude larger than electrical drift-driven transport during nanosecond pulses. While field-assisted charge entry and the magnitude of flux favor transport during nanosecond pulses, these effects are too small to overcome the orders of magnitude more time available for post-pulse transport. Therefore, the basic conclusion that essentially all transmembrane molecular transport occurs post-pulse holds across the plausible range of relevant parameters. Our analysis shows that a primary direct consequence of nanosecond electric pulses is the creation (or maintenance) of large populations of small pores in cell membranes that govern post-pulse transmembrane transport of small ions and molecules. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Picosecond absorption relaxation measured with nanosecond laser photoacoustics

    OpenAIRE

    Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin; Wang, Lihong V.

    2010-01-01

    Picosecond absorption relaxation—central to many disciplines—is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, b...

  11. Guiding of Long-Distance Electric Discharges by Combined Femtosecond and Nanosecond Pulses Emitted by Hybrid KrF Laser System

    Science.gov (United States)

    2014-01-30

    laser pulse initiated HV discharge with a time delay of tens nanoseconds – evidently it is developing due to an avalanche -like growth of electron...AFRL-AFOSR-UK-TR-2014-0040 Guiding of long-distance electric discharges by combined femtosecond and nanosecond pulses emitted by...and guiding electric discharge , KrF laser, femtosecond pulse , nanosecond pulse , filamentation, plasma channel, lightning control, laser control of

  12. [Mechanism of ablation with nanosecond pulsed electric field].

    Science.gov (United States)

    Cen, Chao; Chen, Xin-hua; Zheng, Shu-sen

    2015-11-01

    Nanosecond pulsed electric field ablation has been widely applied in clinical cancer treatment, while its molecular mechanism is still unclear. Researchers have revealed that nanosecond pulsed electric field generates nanopores in plasma membrane, leading to a rapid influx of Ca²⁺; it has specific effect on intracellular organelle membranes, resulting in endoplasmic reticulum injuries and mitochondrial membrane potential changes. In addition, it may also change cellular morphology through damage of cytoskeleton. This article reviews the recent research advances on the molecular mechanism of cell membrane and organelle changes induced by nanosecond pulsed electric field ablation.

  13. New approach to the dosimetry of ionizing radiations by fluorescence measurement, according to the single photon counting technique, correlated in time at the nanosecond scale

    International Nuclear Information System (INIS)

    Sohier, Till

    2011-01-01

    This research thesis reports the first fundamental study of the dosimetry of charged and gamma radiations by measurement of fluorescence resolved in time at a nanosecond scale, in organic matter. This method allows an in-depth and real-time analysis of the deposited dose, while taking ionisation as well as excitation processes into account. The author describes mechanisms of interaction and deposition of energy on dense matter, reports the detailed study of the ion-matter interaction, and the interaction of secondary electrons produced within traces. He addresses mechanisms of energy relaxation, and more particularly the study or organic scintillators. Then, he presents the adopted experimental approach: experimental observation with a statistic reconstitution of the curve representing the intensity of the emitted fluorescence in time and with a nanosecond resolution by using a scintillating sensor for time correlated single photon counting (TCSPC). The next part reports the development of an experimental multi-modal platform for dosimetry by TCSPC aimed at the measurement of fluorescence decays under pulsed excitation (nanosecond pulsed ion beams) and continuous flow excitation (non pulsed beams and radioactive sources). Experimental results are then presented for fluorescence measurements, and compared with measurements obtained by using an ionization chamber under the same irradiation conditions: dose deposited by hellions and carbon ions within polyvinyl toluene and polyethylene terephthalate, use of scintillating optic fibers under gamma irradiation of Caesium 137 and Cobalt 60. A new experimental approach is finally presented to perform dosimetry measurements while experimentally ignoring luminescence produced by Cerenkov effect [fr

  14. Nanosecond high-power dense microplasma switch for visible light

    Energy Technology Data Exchange (ETDEWEB)

    Bataller, A., E-mail: bataller@physics.ucla.edu; Koulakis, J.; Pree, S.; Putterman, S. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States)

    2014-12-01

    Spark discharges in high-pressure gas are known to emit a broadband spectrum during the first 10 s of nanoseconds. We present calibrated spectra of high-pressure discharges in xenon and show that the resulting plasma is optically thick. Laser transmission data show that such a body is opaque to visible light, as expected from Kirchoff's law of thermal radiation. Nanosecond framing images of the spark absorbing high-power laser light are presented. The sparks are ideal candidates for nanosecond, high-power laser switches.

  15. THE RISE TIME OF NORMAL AND SUBLUMINOUS TYPE Ia SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Gaitan, S.; Perrett, K.; Carlberg, R. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. george Street, Toronto, ON M5S 3H4 (Canada); Conley, A. [Center for Astrophysics and Space Astronomy, University of Colorado, 593 UCB, Boulder, CO 80309-0593 (United States); Bianco, F. B.; Howell, D. A.; Graham, M. L. [Department of Physics, University of California, Santa Barbara, Broida Hall, Mail Code 9530, Santa Barbara, CA 93106-9530 (United States); Sullivan, M.; Hook, I. M. [Department of Physics (Astrophysics), University of Oxford, DWB, Keble Road, Oxford, OX1 3RH (United Kingdom); Astier, P.; Balland, C.; Fourmanoit, N.; Guy, J.; Hardin, D.; Pain, R. [LPNHE, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Balam, D. [Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Basa, S. [Laboratoire d' Astrophysique de Marseille, Pole de l' Etoile Site de Chateau-Gombert, 38, rue Frederic Joliot-Curie, 13388 Marseille cedex 13 (France); Fouchez, D. [CPPM, CNRS-IN2P3 and University Aix Marseille II, Case 907, 13288 Marseille cedex 9 (France); Lidman, C. [Australian Astronomical Observatory, P.O. Box 296, Epping, NSW 1710 (Australia); Palanque-Delabrouille, N., E-mail: gonzalez@astro.utoronto.ca [DSM/IRFU/SPP, CEA-Saclay, F-91191 Gif-sur-Yvette (France); and others

    2012-01-20

    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{sup +0.18}{sub -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{sup +0.47}{sub -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{sup +0.81}{sub -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{sub Sun} of {sup 56}Ni synthesized in the explosion. Our conclusions are the same for the single-stretch and two-stretch parameterizations of the light curve.

  16. Production of atmospheric pressure diffuse nanosecond pulsed dielectric barrier discharge using the array needles-plate electrode in air

    International Nuclear Information System (INIS)

    Yang Dezheng; Wang Wenchun; Jia Li; Nie Dongxia; Shi Hengchao

    2011-01-01

    In this paper, a bidirectional high pulse voltage with 20 ns rising time is employed to generate an atmospheric pressure diffuse dielectric barrier discharge using the array needles-plate electrode configuration. Both double needle and multiple needle electrode configurations nanosecond pulsed dielectric barrier discharges are investigated. It is found that a diffuse discharge plasma with low gas temperature can be obtained, and the plasma volume increases with the increase of the pulse peak voltage, but remains almost constant with the increase of the pulse repetition rate. In addition to showing the potential application on a topographically nonuniform surface treatment of the discharge, the multiple needle-plate electrode configuration with different needle-plate electrode gaps are also employed to generate diffuse discharge plasma.

  17. High-Voltage, Multiphasic, Nanosecond Pulses to Modulate Cellular Responses.

    Science.gov (United States)

    Ryan, Hollie A; Hirakawa, Shinji; Yang, Enbo; Zhou, Chunrong; Xiao, Shu

    2018-04-01

    Nanosecond electric pulses are an effective power source in plasma medicine and biological stimulation, in which biophysical responses are governed by peak power and not energy. While uniphasic nanosecond pulse generators are widely available, the recent discovery that biological effects can be uniquely modulated by reversing the polarity of nanosecond duration pulses calls for the development of a multimodal pulse generator. This paper describes a method to generate nanosecond multiphasic pulses for biomedical use, and specifically demonstrates its ability to cancel or enhance cell swelling and blebbing. The generator consists of a series of the fundamental module, which includes a capacitor and a MOSFET switch. A positive or a negative phase pulse module can be produced based on how the switch is connected. Stacking the modules in series can increase the voltage up to 5 kV. Multiple stacks in parallel can create multiphase outputs. As each stack is independently controlled and charged, multiphasic pulses can be created to produce flexible and versatile pulse waveforms. The circuit topology can be used for high-frequency uniphasic or biphasic nanosecond burst pulse production, creating numerous opportunities for the generator in electroporation applications, tissue ablation, wound healing, and nonthermal plasma generation.

  18. Evolution of metastable state molecules N2(A3Σu+) in a nanosecond pulsed discharge: A particle-in-cell/Monte Carlo collisions simulation

    International Nuclear Information System (INIS)

    Gao Liang; Sun Jizhong; Feng Chunlei; Bai Jing; Ding Hongbin

    2012-01-01

    A particle-in-cell plus Monte Carlo collisions method has been employed to investigate the nitrogen discharge driven by a nanosecond pulse power source. To assess whether the production of the metastable state N 2 (A 3 Σ u + ) can be efficiently enhanced in a nanosecond pulsed discharge, the evolutions of metastable state N 2 (A 3 Σ u + ) density and electron energy distribution function have been examined in detail. The simulation results indicate that the ultra short pulse can modulate the electron energy effectively: during the early pulse-on time, high energy electrons give rise to quick electron avalanche and rapid growth of the metastable state N 2 (A 3 Σ u + ) density. It is estimated that for a single pulse with amplitude of -9 kV and pulse width 30 ns, the metastable state N 2 (A 3 Σ u + ) density can achieve a value in the order of 10 9 cm -3 . The N 2 (A 3 Σ u + ) density at such a value could be easily detected by laser-based experimental methods.

  19. Evolution of metastable state molecules N2(A3 Σu+) in a nanosecond pulsed discharge: A particle-in-cell/Monte Carlo collisions simulation

    Science.gov (United States)

    Gao, Liang; Sun, Jizhong; Feng, Chunlei; Bai, Jing; Ding, Hongbin

    2012-01-01

    A particle-in-cell plus Monte Carlo collisions method has been employed to investigate the nitrogen discharge driven by a nanosecond pulse power source. To assess whether the production of the metastable state N2(A3 Σu+) can be efficiently enhanced in a nanosecond pulsed discharge, the evolutions of metastable state N2(A3 Σu+) density and electron energy distribution function have been examined in detail. The simulation results indicate that the ultra short pulse can modulate the electron energy effectively: during the early pulse-on time, high energy electrons give rise to quick electron avalanche and rapid growth of the metastable state N2(A3 Σu+) density. It is estimated that for a single pulse with amplitude of -9 kV and pulse width 30 ns, the metastable state N2(A3 Σu+) density can achieve a value in the order of 109 cm-3. The N2(A3 Σu+) density at such a value could be easily detected by laser-based experimental methods.

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

    Science.gov (United States)

    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.

  1. Fast-timing methods for semiconductor detectors

    International Nuclear Information System (INIS)

    Spieler, H.

    1982-03-01

    The basic parameters are discussed which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter

  2. Nanosecond time-resolved investigations using the in situ of dynamic transmission electron microscope (DTEM)

    International Nuclear Information System (INIS)

    LaGrange, Thomas; Campbell, Geoffrey H.; Reed, B.W.; Taheri, Mitra; Pesavento, J. Bradley; Kim, Judy S.; Browning, Nigel D.

    2008-01-01

    Most biological processes, chemical reactions and materials dynamics occur at rates much faster than can be captured with standard video rate acquisition methods in transmission electron microscopes (TEM). Thus, there is a need to increase the temporal resolution in order to capture and understand salient features of these rapid materials processes. This paper details the development of a high-time resolution dynamic transmission electron microscope (DTEM) that captures dynamics in materials with nanosecond time resolution. The current DTEM performance, having a spatial resolution <10 nm for single-shot imaging using 15 ns electron pulses, will be discussed in the context of experimental investigations in solid state reactions of NiAl reactive multilayer films, the study of martensitic transformations in nanocrystalline Ti and the catalytic growth of Si nanowires. In addition, this paper will address the technical issues involved with high current, electron pulse operation and the near-term improvements to the electron optics, which will greatly improve the signal and spatial resolutions, and to the laser system, which will allow tailored specimen and photocathode drive conditions

  3. Nanosecond time-resolved investigations using the in situ of dynamic transmission electron microscope (DTEM)

    Energy Technology Data Exchange (ETDEWEB)

    LaGrange, Thomas [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States)], E-mail: lagrange@llnl.gov; Campbell, Geoffrey H.; Reed, B.W.; Taheri, Mitra; Pesavento, J. Bradley [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Kim, Judy S.; Browning, Nigel D. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Department of Chemical Engineering and Materials Science, University of California, One Shields Avenue, Davis, CA 95616 (United States)

    2008-10-15

    Most biological processes, chemical reactions and materials dynamics occur at rates much faster than can be captured with standard video rate acquisition methods in transmission electron microscopes (TEM). Thus, there is a need to increase the temporal resolution in order to capture and understand salient features of these rapid materials processes. This paper details the development of a high-time resolution dynamic transmission electron microscope (DTEM) that captures dynamics in materials with nanosecond time resolution. The current DTEM performance, having a spatial resolution <10 nm for single-shot imaging using 15 ns electron pulses, will be discussed in the context of experimental investigations in solid state reactions of NiAl reactive multilayer films, the study of martensitic transformations in nanocrystalline Ti and the catalytic growth of Si nanowires. In addition, this paper will address the technical issues involved with high current, electron pulse operation and the near-term improvements to the electron optics, which will greatly improve the signal and spatial resolutions, and to the laser system, which will allow tailored specimen and photocathode drive conditions.

  4. Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers

    Science.gov (United States)

    The Pierre Auger Collaboration

    2016-01-01

    To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independent method is used to cross-check that indeed we reach a nanosecond-scale timing accuracy by this correction. First, we operate a ``beacon transmitter'' which emits defined sine waves detected by AERA antennas recorded within the physics data. The relative phasing of these sine waves can be used to correct for GPS clock drifts. In addition to this, we observe radio pulses emitted by commercial airplanes, the position of which we determine in real time from Automatic Dependent Surveillance Broadcasts intercepted with a software-defined radio. From the known source location and the measured arrival times of the pulses we determine relative timing offsets between radio detector stations. We demonstrate with a combined analysis that the two methods give a consistent timing calibration with an accuracy of 2 ns or better. Consequently, the beacon method alone can be used in the future to continuously determine and correct for GPS clock drifts in each individual event measured by AERA.

  5. Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers

    International Nuclear Information System (INIS)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E.J.; Al Samarai, I.; Albuquerque, I.F.M.; Allekotte, I.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.

    2016-01-01

    To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independent method is used to cross-check that indeed we reach a nanosecond-scale timing accuracy by this correction. First, we operate a ''beacon transmitter'' which emits defined sine waves detected by AERA antennas recorded within the physics data. The relative phasing of these sine waves can be used to correct for GPS clock drifts. In addition to this, we observe radio pulses emitted by commercial airplanes, the position of which we determine in real time from Automatic Dependent Surveillance Broadcasts intercepted with a software-defined radio. From the known source location and the measured arrival times of the pulses we determine relative timing offsets between radio detector stations. We demonstrate with a combined analysis that the two methods give a consistent timing calibration with an accuracy of 2 ns or better. Consequently, the beacon method alone can be used in the future to continuously determine and correct for GPS clock drifts in each individual event measured by AERA

  6. Energy efficiency in nanoscale synthesis using nanosecond plasmas.

    Science.gov (United States)

    Pai, David Z; Ken Ostrikov, Kostya; Kumar, Shailesh; Lacoste, Deanna A; Levchenko, Igor; Laux, Christophe O

    2013-01-01

    We report a nanoscale synthesis technique using nanosecond-duration plasma discharges. Voltage pulses 12.5 kV in amplitude and 40 ns in duration were applied repetitively at 30 kHz across molybdenum electrodes in open ambient air, generating a nanosecond spark discharge that synthesized well-defined MoO₃ nanoscale architectures (i.e. flakes, dots, walls, porous networks) upon polyamide and copper substrates. No nitrides were formed. The energy cost was as low as 75 eV per atom incorporated into a nanostructure, suggesting a dramatic reduction compared to other techniques using atmospheric pressure plasmas. These findings show that highly efficient synthesis at atmospheric pressure without catalysts or external substrate heating can be achieved in a simple fashion using nanosecond discharges.

  7. Nanosecond time-resolved characterization of a pentacene-based room-temperature MASER

    Science.gov (United States)

    Salvadori, Enrico; Breeze, Jonathan D.; Tan, Ke-Jie; Sathian, Juna; Richards, Benjamin; Fung, Mei Wai; Wolfowicz, Gary; Oxborrow, Mark; Alford, Neil McN.; Kay, Christopher W. M.

    2017-01-01

    The performance of a room temperature, zero-field MASER operating at 1.45 GHz has been examined. Nanosecond laser pulses, which are essentially instantaneous on the timescale of the spin dynamics, allow the visible-to-microwave conversion efficiency and temporal response of the MASER to be measured as a function of excitation energy. It is observed that the timing and amplitude of the MASER output pulse are correlated with the laser excitation energy: at higher laser energy, the microwave pulses have larger amplitude and appear after shorter delay than those recorded at lower laser energy. Seeding experiments demonstrate that the output variation may be stabilized by an external source and establish the minimum seeding power required. The dynamics of the MASER emission may be modeled by a pair of first order, non-linear differential equations, derived from the Lotka-Volterra model (Predator-Prey), where by the microwave mode of the resonator is the predator and the spin polarization in the triplet state of pentacene is the prey. Simulations allowed the Einstein coefficient of stimulated emission, the spin-lattice relaxation and the number of triplets contributing to the MASER emission to be estimated. These are essential parameters for the rational improvement of a MASER based on a spin-polarized triplet molecule. PMID:28169331

  8. Generator of pulses with the nanosecond duration and accurate amplitude using the digital control in the CAMAC standard

    International Nuclear Information System (INIS)

    Basiladze, S.G.; Nguen Kuang Min'

    1980-01-01

    A generator of square-wave fine-amplitude nanosecond pulses is described. The generator is primarily intended for checking the performances of fast electronics analog-to-digital units with the help of a computer. In addition to digital control the pulse amplitude can be controlled manually or by the external voltage. Basic circuits of main generator assemblies: a triggering circuit, transistor key and digital-to-analog converter are given. Output pulses produced by the generator have the following parameters: the amplitude from - 0.15 to - 10 V (smooth or gradual, with a minimum step of 5 mV), the rising and decay pulse times approximately 2 ns, the maximum repetition frequency 10 kHz, the control linearity at a pulse duration of more than 50 ns 0.15%. A double-width CAMAC cell accomodates two generators

  9. Fast timing methods for semiconductor detectors. Revision

    International Nuclear Information System (INIS)

    Spieler, H.

    1984-10-01

    This tutorial paper discusses the basic parameters which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter

  10. Compact sub-nanosecond pulse seed source with diode laser driven by a high-speed circuit

    Science.gov (United States)

    Wang, Xiaoqian; Wang, Bo; Wang, Junhua; Cheng, Wenyong

    2018-06-01

    A compact sub-nanosecond pulse seed source with 1550 nm diode laser (DL) was obtained by employing a high-speed circuit. The circuit mainly consisted of a short pulse generator and a short pulse driver. The short pulse generator, making up of a complex programmable logic device (CPLD), a level translator, two programmable delay chips and an AND gate chip, output a triggering signal to control metal-oxide-semiconductor field-effect transistor (MOSFET) switch of the short pulse driver. The MOSFET switch with fast rising time and falling time both shorter than 1 ns drove the DL to emit short optical pulses. Performances of the pulse seed source were tested. The results showed that continuously adjustable repetition frequency ranging from 500 kHz to 100 MHz and pulse duration in the range of 538 ps to 10 ns were obtained, respectively. 537 μW output was obtained at the highest repetition frequency of 100 MHz with the shortest pulse duration of 538 ps. These seed pulses were injected into an fiber amplifier, and no optical pulse distortions were found.

  11. Plasma density enhancement in atmospheric-pressure dielectric-barrier discharges by high-voltage nanosecond pulse in the pulse-on period: a PIC simulation

    International Nuclear Information System (INIS)

    Sang Chaofeng; Sun Jizhong; Wang Dezhen

    2010-01-01

    A particle-in-cell (PIC) plus Monte Carlo collision simulation is employed to investigate how a sustainable atmospheric pressure single dielectric-barrier discharge responds to a high-voltage nanosecond pulse (HVNP) further applied to the metal electrode. The results show that the HVNP can significantly increase the plasma density in the pulse-on period. The ion-induced secondary electrons can give rise to avalanche ionization in the positive sheath, which widens the discharge region and enhances the plasma density drastically. However, the plasma density stops increasing as the applied pulse lasts over certain time; therefore, lengthening the pulse duration alone cannot improve the discharge efficiency further. Physical reasons for these phenomena are then discussed.

  12. Plasma density enhancement in atmospheric-pressure dielectric-barrier discharges by high-voltage nanosecond pulse in the pulse-on period: a PIC simulation

    Science.gov (United States)

    Sang, Chaofeng; Sun, Jizhong; Wang, Dezhen

    2010-02-01

    A particle-in-cell (PIC) plus Monte Carlo collision simulation is employed to investigate how a sustainable atmospheric pressure single dielectric-barrier discharge responds to a high-voltage nanosecond pulse (HVNP) further applied to the metal electrode. The results show that the HVNP can significantly increase the plasma density in the pulse-on period. The ion-induced secondary electrons can give rise to avalanche ionization in the positive sheath, which widens the discharge region and enhances the plasma density drastically. However, the plasma density stops increasing as the applied pulse lasts over certain time; therefore, lengthening the pulse duration alone cannot improve the discharge efficiency further. Physical reasons for these phenomena are then discussed.

  13. Measurement of the Rise-Time in a Single Sided Ladder Detector

    International Nuclear Information System (INIS)

    Gerber, C.E.

    1997-01-01

    In this note we report on the measurement of the preamplifier output rise time for a SVXII chip mounted on a D0 single sided ladder. The measurements were performed on the ladder 001-883-L, using the laser test stand of Lab D. The rise time was measured for different values of the response (or bandwidth) of the preamplifier. As a bigger bandwidth results in longer rise times and therefore in less noise, the largest possible bandwidth consistent with the time between bunch crossings should be chosen to operate the detectors. The rise time is defined as the time elapsed between 10% and 90% of the charge is collected. It is also interesting to measure the time for full charge collection and the percentage of charge collected in 132 ns and 396 ns. The results are shown in table 1, for bandwidths between 2 and 63 (binary numbers). The uncertainty on the time measurement is considered to be ∼ 10 ns. Figure 1 schematically defines the four quantities measured: rise time, time of full charge collection, and percentage of charge collected in 132 ns and 396 ns. Figures 2 to 8 are the actual measurements for bandwidths of 2, 4, 8, 12, 24, 32 and 63. Figure 9 is a second measurement for BW=24, used as a consistency check of the system and the time measurement performed on the plots. The data indicate that the single sided ladders can be operated at BW=63 for 396 ns and BW=12 for 132 ns, achieving full charge collection. This will result in smaller noise than originally anticipated.

  14. Nanosecond-Timescale Intra-Bunch-Train Feedback for the Linear Collider: Results of the FONT2 Run

    International Nuclear Information System (INIS)

    Barlow, R.; Dufau, M.; Kalinin, A.; Daresbury; Myatt, G.; Perry, C.; Oxford U.; Burrows, P.N.; Hartin, T.; Hussain, S.M.; Molloy, S.; White, G.R.; Queen Mary, U. of London; Adolphsen, C.; Frisch, J.C.; Hendrickson, L.; Jobe, R.K.; Markiewicz, T.; McCormick, D.J.; Nelson, J.; Ross, M.C.; Smith, S.; Smith, T.J.; SLAC

    2005-01-01

    We report on experimental results from the December 2003/January 2004 data run of the Feedback On Nanosecond Timescales (FONT) experiment at the Next Linear Collider Test Accelerator at SLAC. We built a second-generation prototype intra-train beam-based feedback system incorporating beam position monitors, fast analogue signal processors, a feedback circuit, fast-risetime amplifiers and stripline kickers. We applied a novel real-time charge-normalization scheme to account for beam current variations along the train. We used the system to correct the position of the 170-nanosecond-long bunchtrain at NLCTA. We achieved a latency of 53 nanoseconds, representing a significant improvement on FONT1 (2002), and providing a demonstration of intra-train feedback for the Linear Collider

  15. The role of nanosecond electric pulse-induced mechanical stress in cellular nanoporation

    Science.gov (United States)

    Roth, Caleb C.

    Background: Exposures of cells to very short (less than 1 microsecond) electric pulses in the megavolt/meter range have been shown to cause a multitude of effects, both physical and molecular in nature. Physically, nanosecond electrical pulse exposure can disrupt the plasma membrane, leading to a phenomenon known as nanoporation. Nanoporation is the production of nanometer sized holes (less than 2 nanometers in diameter) that can persist for up to fifteen minutes, allowing the flow of ions into and out of the cell. Nanoporation can lead to secondary physical effects, such as cellular swelling, shrinking and blebbing. Molecularly, nanosecond electrical pulses have been shown to activate signaling pathways, produce oxidative stress, stimulate hormone secretion and induce both apoptotic and necrotic death. The mechanism by which nanosecond electrical pulses cause molecular changes is unknown; however, it is thought the flow of ions, such as calcium, into the cell via nanopores, could be a major cause. The ability of nanosecond electrical pulses to cause membranes to become permeable and to induce apoptosis makes the technology a desirable modality for cancer research; however, the lack of understanding regarding the mechanisms by which nanosecond electrical pulses cause nanoporation impedes further development of this technology. This dissertation documents the genomic and proteomic responses of cells exposed to nanosecond electrical pulses and describes in detail the biophysical effects of these electrical pulses, including the demonstration for the first time of the generation of acoustic pressure transients capable of disrupting plasma membranes and possibly contributing to nanoporation. Methods: Jurkat, clone E6-1 (human lymphocytic cell line), U937 (human lymphocytic cell line), Chinese hamster ovarian cells and adult primary human dermal fibroblasts exposed to nanosecond electrical pulses were subjected to a variety of molecular assays, including flow cytometry

  16. Experimental Study of SO2 Removal by Pulsed DBD Along with the Application of Magnetic Field

    International Nuclear Information System (INIS)

    Rong Mingzhe; Liu Dingxin; Wang Xiaohua; Wang Junhua

    2007-01-01

    Dielectric barrier discharge (DBD) for SO 2 removal from indoor air is investigated. In order to improve the removal efficiency, two novel methods are combined in this paper, namely by applying a pulsed driving voltage with nanosecond rising time and applying a magnetic field. For SO 2 removal efficiency, different matches of electric field and magnetic field are discussed. And nanosecond rising edge pulsed power supply and microsecond rising edge pulsed power supply are compared. It can be concluded that a pulsed DBD with nanosecond rising edge should be adopted, and electrical field and magnetic field should be applied in an appropriate match

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  18. Plasma plume expansion dynamics in nanosecond Nd:YAG laserosteotome

    Science.gov (United States)

    Abbasi, Hamed; Rauter, Georg; Guzman, Raphael; Cattin, Philippe C.; Zam, Azhar

    2018-02-01

    In minimal invasive laser osteotomy precise information about the ablation process can be obtained with LIBS in order to avoid carbonization, or cutting of wrong types of tissue. Therefore, the collecting fiber for LIBS needs to be optimally placed in narrow cavities in the endoscope. To determine this optimal placement, the plasma plume expansion dynamics in ablation of bone tissue by the second harmonic of a nanosecond Nd:YAG laser at 532 nm has been studied. The laserinduced plasma plume was monitored in different time delays, from one nanosecond up to one hundred microseconds. Measurements were performed using high-speed gated illumination imaging. The expansion features were studied using illumination of the overall visible emission by using a gated intensified charged coupled device (ICCD). The camera was capable of having a minimum gate width (Optical FWHM) of 3 ns and the timing resolution (minimum temporal shift of the gate) of 10 ps. The imaging data were used to generate position-time data of the luminous plasma-front. Moreover, the velocity of the plasma plume expansion was studied based on the time-resolved intensity data. By knowing the plasma plume profile over time, the optimum position (axial distance from the laser spot) of the collecting fiber and optimal time delay (to have the best signal to noise ratio) in spatial-resolved and time-resolved laser-induced breakdown spectroscopy (LIBS) can be determined. Additionally, the function of plasma plume expansion could be used to study the shock wave of the plasma plume.

  19. Nanosecond UV lasers stimulate transient Ca2+ elevations in human hNT astrocytes.

    Science.gov (United States)

    Raos, B J; Graham, E S; Unsworth, C P

    2017-06-01

    Astrocytes respond to various stimuli resulting in intracellular Ca 2+ signals that can propagate through organized functional networks. Recent literature calls for the development of techniques that can stimulate astrocytes in a fast and highly localized manner to emulate more closely the characteristics of astrocytic Ca 2+ signals in vivo. In this article we demonstrate, for the first time, how nanosecond UV lasers are capable of reproducibly stimulating Ca 2+ transients in human hNT astrocytes. We report that laser pulses with a beam energy of 4-29 µJ generate transient increases in cytosolic Ca 2+ . These Ca 2+ transients then propagate to adjacent astrocytes as intercellular Ca 2+ waves. We propose that nanosecond laser stimulation provides a valuable tool for enabling the study of Ca 2+ dynamics in human astrocytes at both a single cell and network level. Compared to previously developed techniques nanosecond laser stimulation has the advantage of not requiring loading of photo-caged or -sensitising agents, is non-contact, enables stimulation with a high spatiotemporal resolution and is comparatively cost effective.

  20. Evaluation of material dispersion using a nanosecond optical pulse radiator.

    Science.gov (United States)

    Horiguchi, M; Ohmori, Y; Miya, T

    1979-07-01

    To study the material dispersion effects on graded-index fibers, a method for measuring the material dispersion in optical glass fibers has been developed. Nanosecond pulses in the 0.5-1.7-microm region are generated by a nanosecond optical pulse radiator and grating monochromator. These pulses are injected into a GeO(2)-P(2)0(5)-doped silica graded-index fiber. Relative time delay changes between different wavelengths are used to determine material dispersion, core glass refractive index, material group index, and optimum profile parameter of the graded-index fiber. From the measured data, the optimum profile parameter on the GeO(2)-P(2)O(5)-doped silica graded-index fiber could be estimated to be 1.88 at 1.27 microm of the material dispersion free wavelength region and 1.82 at 1.55 microm of the lowest-loss wavelength region in silica-based optical fiber waveguides.

  1. PNG-300 a nanosecond pulsed neutron generator

    International Nuclear Information System (INIS)

    Sztaricskai, T.; Vasvary, L.; Petoe, G.C.; Devkin, B.V.

    1985-01-01

    The design and operation of a nanosecond-pulse neutron generator is reported. It was constructed for the measurement of prompt neutron and gamma radiation in experimental studies of fast neutron reactions by time of flight techniques. The acceleration voltage is 300 kV and the total resolution of the generator-neutron spectrometer system is 2 ns. The ion-optical system, the vacuum system and the control of the neutron generator is described in detail. The equipment was used for prompt neutron and gamma radiation induced in construction materials. (R.P.)

  2. Picosecond absorption relaxation measured with nanosecond laser photoacoustics.

    Science.gov (United States)

    Danielli, Amos; Favazza, Christopher P; Maslov, Konstantin; Wang, Lihong V

    2010-10-18

    Picosecond absorption relaxation-central to many disciplines-is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural-including strongly scattering and nonfluorescent-materials.

  3. Time-resolved analysis of thickness-dependent dewetting and ablation of silver films upon nanosecond laser irradiation

    International Nuclear Information System (INIS)

    Qi, Dongfeng; Paeng, Dongwoo; Yeo, Junyeob; Kim, Eunpa; Wang, Letian; Grigoropoulos, Costas P.; Chen, Songyan

    2016-01-01

    Nanosecond pulsed laser dewetting and ablation of thin silver films is investigated by time-resolved imaging. Laser pulses of 532 nm wavelength and 5 ns temporal width are irradiated on silver films of different thicknesses (50 nm, 80 nm, and 350 nm). Below the ablation threshold, it is observed that the dewetting process does not conclude until 630 ns after the laser irradiation for all samples, forming droplet-like particles in the spot central region. At higher laser intensities, ablative material removal occurs in the spot center. Cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter at about 700 ns following the laser pulse exposure. In addition to these features, droplet fingers are superposed upon irradiation of 350-nm thick silver films with higher intensity.

  4. Time-resolved analysis of thickness-dependent dewetting and ablation of silver films upon nanosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Dongfeng [Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Semiconductor Photonics Research Center, Department of Physics, Xiamen University, Xiamen 361005 (China); Paeng, Dongwoo; Yeo, Junyeob; Kim, Eunpa; Wang, Letian; Grigoropoulos, Costas P., E-mail: cgrigoro@berkeley.edu [Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Chen, Songyan [Semiconductor Photonics Research Center, Department of Physics, Xiamen University, Xiamen 361005 (China)

    2016-05-23

    Nanosecond pulsed laser dewetting and ablation of thin silver films is investigated by time-resolved imaging. Laser pulses of 532 nm wavelength and 5 ns temporal width are irradiated on silver films of different thicknesses (50 nm, 80 nm, and 350 nm). Below the ablation threshold, it is observed that the dewetting process does not conclude until 630 ns after the laser irradiation for all samples, forming droplet-like particles in the spot central region. At higher laser intensities, ablative material removal occurs in the spot center. Cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter at about 700 ns following the laser pulse exposure. In addition to these features, droplet fingers are superposed upon irradiation of 350-nm thick silver films with higher intensity.

  5. Integrated circuits with emitter coupling and their application in nanosecond nuclear electronics

    International Nuclear Information System (INIS)

    Basiladze, S.G.

    1976-01-01

    Principal static and dynamic characteristics are considered of integrated circuits with emitter coupling, as well as problems of signal transmission. Diagrams are given of amplifiers, discriminators, time interval drivers, generators, etc. Systems and units of nanosecond electronics employing integrated circuits with emitter coupling are briefly described

  6. Rise time spectroscopy in cadmium telluride detectors

    International Nuclear Information System (INIS)

    Scharager, Claude; Siffert, Paul; Carnet, Bernard; Le Meur, Roger.

    1980-11-01

    By a simultaneous analysis of rise time and pulse amplitude distributions of the signals issued from various cadmium telluride detectors, it is possible to obtain informations about surface and bulk trapping, field distribution within the detectors, as well as charge collection and transport properties. These investigations have been performed on both pure and chlorine doped and materials for various surfaces preparation conditions [fr

  7. Development of a fast rise-time, high-voltage pulse generator

    International Nuclear Information System (INIS)

    Zhang Yanxia; Zhu Jie; Li Xianyou

    2006-01-01

    In order to test the attenuation of the system, a fast rise-time, high-voltage pulse generator is required for the fast pulse signal measurement. The paper presents the development of the generator. More emphasis is paid on the discussion of the difficulties occurring in the circuit debugging and their resolutions. The output rise-time of the generator is 700 ps, the amplitude is adjustable in the range of 0 to 500 V, the pulse-width is adjustable in the range of 4ns to 1μs. (authors)

  8. A scheme for recording a fast process at nanosecond scale by using digital holographic interferometry with continuous wave laser

    Science.gov (United States)

    Wang, Jun; Zhao, Jianlin; Di, Jianglei; Jiang, Biqiang

    2015-04-01

    A scheme for recording fast process at nanosecond scale by using digital holographic interferometry with continuous wave (CW) laser is described and demonstrated experimentally, which employs delayed-time fibers and angular multiplexing technique and can realize the variable temporal resolution at nanosecond scale and different measured depths of object field at certain temporal resolution. The actual delay-time is controlled by two delayed-time fibers with different lengths. The object field information in two different states can be simultaneously recorded in a composite hologram. This scheme is also suitable for recording fast process at picosecond scale, by using an electro-optic modulator.

  9. Interaction of gold nanoparticles with nanosecond laser pulses: Nanoparticle heating

    International Nuclear Information System (INIS)

    Nedyalkov, N.N.; Imamova, S.E.; Atanasov, P.A.; Toshkova, R.A.; Gardeva, E.G.; Yossifova, L.S.; Alexandrov, M.T.; Obara, M.

    2011-01-01

    Theoretical and experimental results on the heating process of gold nanoparticles irradiated by nanosecond laser pulses are presented. The efficiency of particle heating is demonstrated by in-vitro photothermal therapy of human tumor cells. Gold nanoparticles with diameters of 40 and 100 nm are added as colloid in the cell culture and the samples are irradiated by nanosecond pulses at wavelength of 532 nm delivered by Nd:YAG laser system. The results indicate clear cytotoxic effect of application of nanoparticle as more efficient is the case of using particles with diameter of 100 nm. The theoretical analysis of the heating process of nanoparticle interacting with laser radiation is based on the Mie scattering theory, which is used for calculation of the particle absorption coefficient, and two-dimensional heat diffusion model, which describes the particle and the surrounding medium temperature evolution. Using this model the dependence of the achieved maximal temperature in the particles on the applied laser fluence and time evolution of the particle temperature is obtained.

  10. Interaction of gold nanoparticles with nanosecond laser pulses: Nanoparticle heating

    Science.gov (United States)

    Nedyalkov, N. N.; Imamova, S. E.; Atanasov, P. A.; Toshkova, R. A.; Gardeva, E. G.; Yossifova, L. S.; Alexandrov, M. T.; Obara, M.

    2011-04-01

    Theoretical and experimental results on the heating process of gold nanoparticles irradiated by nanosecond laser pulses are presented. The efficiency of particle heating is demonstrated by in-vitro photothermal therapy of human tumor cells. Gold nanoparticles with diameters of 40 and 100 nm are added as colloid in the cell culture and the samples are irradiated by nanosecond pulses at wavelength of 532 nm delivered by Nd:YAG laser system. The results indicate clear cytotoxic effect of application of nanoparticle as more efficient is the case of using particles with diameter of 100 nm. The theoretical analysis of the heating process of nanoparticle interacting with laser radiation is based on the Mie scattering theory, which is used for calculation of the particle absorption coefficient, and two-dimensional heat diffusion model, which describes the particle and the surrounding medium temperature evolution. Using this model the dependence of the achieved maximal temperature in the particles on the applied laser fluence and time evolution of the particle temperature is obtained.

  11. Development of an integrated four-channel fast avalanche-photodiode detector system with nanosecond time resolution

    Science.gov (United States)

    Li, Zhenjie; Li, Qiuju; Chang, Jinfan; Ma, Yichao; Liu, Peng; Wang, Zheng; Hu, Michael Y.; Zhao, Jiyong; Alp, E. E.; Xu, Wei; Tao, Ye; Wu, Chaoqun; Zhou, Yangfan

    2017-10-01

    A four-channel nanosecond time-resolved avalanche-photodiode (APD) detector system is developed at Beijing Synchrotron Radiation. It uses a single module for signal processing and readout. This integrated system provides better reliability and flexibility for custom improvement. The detector system consists of three parts: (i) four APD sensors, (ii) four fast preamplifiers and (iii) a time-digital-converter (TDC) readout electronics. The C30703FH silicon APD chips fabricated by Excelitas are used as the sensors of the detectors. It has an effective light-sensitive area of 10 × 10 mm2 and an absorption layer thickness of 110 μm. A fast preamplifier with a gain of 59 dB and bandwidth of 2 GHz is designed to readout of the weak signal from the C30703FH APD. The TDC is realized by a Spartan-6 field-programmable-gate-array (FPGA) with multiphase method in a resolution of 1ns. The arrival time of all scattering events between two start triggers can be recorded by the TDC. The detector has been used for nuclear resonant scattering study at both Advanced Photon Source and also at Beijing Synchrotron Radiation Facility. For the X-ray energy of 14.4 keV, the time resolution, the full width of half maximum (FWHM) of the detector (APD sensor + fast amplifier) is 0.86 ns, and the whole detector system (APD sensors + fast amplifiers + TDC readout electronics) achieves a time resolution of 1.4 ns.

  12. Rugged calorimeter with a fast rise time

    International Nuclear Information System (INIS)

    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%

  13. Comparison of occlusion break responses and vacuum rise times of phacoemulsification systems.

    Science.gov (United States)

    Sharif-Kashani, Pooria; Fanney, Douglas; Injev, Val

    2014-07-30

    Occlusion break surge during phacoemulsification cataract surgery can lead to potential surgical complications. The purpose of this study was to quantify occlusion break surge and vacuum rise time of current phacoemulsification systems used in cataract surgery. Occlusion break surge at vacuum pressures between 200 and 600 mmHg was assessed with the Infiniti® Vision System, the WhiteStar Signature® Phacoemulsification System, and the Centurion® Vision System using gravity-fed fluidics. Centurion Active FluidicsTM were also tested at multiple intraoperative pressure target settings. Vacuum rise time was evaluated for Infiniti, WhiteStar Signature, Centurion, and Stellaris® Vision Enhancement systems. Rise time to vacuum limits of 400 and 600 mmHg was assessed at flow rates of 30 and 60 cc/minute. Occlusion break surge was analyzed by 2-way analysis of variance. The Centurion system exhibited substantially less occlusion break surge than the other systems tested. Surge area with Centurion Active Fluidics was similar to gravity fluidics at an equivalent bottle height. At all Centurion Active Fluidics intraoperative pressure target settings tested, surge was smaller than with Infiniti and WhiteStar Signature. Infiniti had the fastest vacuum rise time and Stellaris had the slowest. No system tested reached the 600-mmHg vacuum limit. In this laboratory study, Centurion had the least occlusion break surge and similar vacuum rise times compared with the other systems tested. Reducing occlusion break surge may increase safety of phacoemulsification cataract surgery.

  14. Evolution of metastable state molecules N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) in a nanosecond pulsed discharge: A particle-in-cell/Monte Carlo collisions simulation

    Energy Technology Data Exchange (ETDEWEB)

    Gao Liang; Sun Jizhong; Feng Chunlei; Bai Jing; Ding Hongbin [School of Physics and Optical Electronic Technology, Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams, Chinese Ministry of Education, Dalian University of Technology, Dalian 116024 (China)

    2012-01-15

    A particle-in-cell plus Monte Carlo collisions method has been employed to investigate the nitrogen discharge driven by a nanosecond pulse power source. To assess whether the production of the metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) can be efficiently enhanced in a nanosecond pulsed discharge, the evolutions of metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density and electron energy distribution function have been examined in detail. The simulation results indicate that the ultra short pulse can modulate the electron energy effectively: during the early pulse-on time, high energy electrons give rise to quick electron avalanche and rapid growth of the metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density. It is estimated that for a single pulse with amplitude of -9 kV and pulse width 30 ns, the metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density can achieve a value in the order of 10{sup 9} cm{sup -3}. The N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density at such a value could be easily detected by laser-based experimental methods.

  15. Comparing the effects of rise time and inspiratory cycling criteria on 6 different mechanical ventilators.

    Science.gov (United States)

    Gonzales, Joshua F; Russian, Christopher J; Gregg Marshall, S; Collins, Kevin P

    2013-03-01

    Inspiratory rise time and cycling criteria are important settings in pressure support ventilation. The purpose of this study was to investigate the impact of minimum and maximum rise time and inspiratory cycling criteria settings on 6 new generation ventilators. Our hypothesis was there would be a difference in the exhaled tidal volume, inspiratory time, and peak flow among 6 different ventilators, based, on change in rise time and cycling criteria. The research utilized a breathing simulator and 4 different ventilator models. All mechanical ventilators were set to a spontaneous mode of ventilation with settings of pressure support 8 cm H2O and PEEP of 5 cm H2O. A minimum and maximum setting for rise time and cycling criteria were examined. Exhaled tidal volume, inspiratory time, and peak flow measurements were recorded for each simulation. Significant (P ventilator. Significant differences in exhaled tidal volume, inspiratory time, and peak flow were observed by adjusting rise time and cycling criteria. This research demonstrates that during pressure support ventilation strategy, adjustments in rise time and/or cycling criteria can produce changes in inspiratory parameters. Obviously, this finding has important implications for practitioners who utilize a similar pressure support strategy when conducting a ventilator wean. Additionally, this study outlines major differences among ventilator manufacturers when considering inspiratory rise time and cycling criteria.

  16. Nanosecond pulsed discharges in N2 and N2/H2O mixtures

    NARCIS (Netherlands)

    Joosten, R.M.; Verreycken, T.; Veldhuizen, van E.M.; Bruggeman, P.J.

    2011-01-01

    Nanosecond pulsed discharges in N2 and N2/H2O at atmospheric pressure between two pin-shaped electrodes are studied. The evolution of the discharge is investigated with time-resolved imaging and optical emission spectroscopy. The discharge consists of three phases, the ignition (mainly molecular

  17. Sodium current inhibition by nanosecond pulsed electric field (nsPEF)--fact or artifact?

    NARCIS (Netherlands)

    Verkerk, Arie O.; van Ginneken, Antoni C. G.; Wilders, Ronald

    2013-01-01

    In two recent publications in Bioelectromagnetics it has been demonstrated that the voltage-gated sodium current (I(Na)) is inhibited in response to a nanosecond pulsed electric field (nsPEF). At the same time, there was an increase in a non-inactivating "leak" current (I(leak)), which was

  18. Nanosecond optical limiting response of sandwich-type neodymium dyphthalocyanine in a co-polymer host

    NARCIS (Netherlands)

    Aneeshkumar, B.N.; Gopinath, P.; Thomas, J.; Vallabhan, C.P.G.; Nampoori, V.P.N.; Radhakrishnan, P.

    2004-01-01

    The nanosecond optical limiting characteristics of sandwich-type neodymium diphthalocyanine in a co-polymer matrix of polymethyl methacrylate (PMMA) and methyl-2-cyanoacrylate have been studied for the first time. The measurements were performed using 9 ns laser pulses generated from a

  19. Numerical Simulation of a Nanosecond-Pulse Discharge for High-Speed Flow Control

    Science.gov (United States)

    Poggie, Jonathan; Adamovich, Igor

    2012-10-01

    Numerical calculations were carried out to examine the physics of the operation of a nanosecond-pulse, single dielectric barrier discharge in a configuration with planar symmetry. This simplified configuration was chosen as a vehicle to develop a physics based nanosecond discharge model, including realistic air plasma chemistry and compressible bulk gas flow. First, a reduced plasma kinetic model was developed by carrying out a sensitivity analysis of zero-dimensional plasma computations with an extended chemical kinetic model. Transient, one- dimensional discharge computations were then carried out using the reduced kinetic model, incorporating a drift-diffusion formulation for each species, a self-consistent computation of the electric potential using the Poisson equation, and a mass-averaged gas dynamic formulation for the bulk gas motion. Discharge parameters (temperature, pressure, and input waveform) were selected to be representative of recent experiments on bow shock control with a nanosecond discharge in a Mach 5 cylinder flow. The computational results qualitatively reproduce many of the features observed in the experiments, including the rapid thermalization of the input electrical energy and the consequent formation of a weak shock wave. At breakdown, input electrical energy is rapidly transformed (over roughly 1 ns) into ionization products, dissociation products, and electronically excited particles, with subsequent thermalization over a relatively longer time-scale (roughly 10 μs).

  20. Numerical investigation of energy transfer for fast gas heating in an atmospheric nanosecond-pulsed DBD under different negative slopes

    International Nuclear Information System (INIS)

    Zhu, Yifei; Wu, Yun; Cui, Wei; Li, Yinghong; Jia, Min

    2013-01-01

    A validated one-dimensional air plasma kinetics model (13 species and 37 processes) for a nanosecond discharge under atmospheric pressure was developed to reveal the energy transfer mechanism for fast gas heating of a plane-to-plane dielectric barrier discharge (DBD). Calculations for voltage profiles with three different negative slopes were performed. Results have shown that 72% of the total heating energy goes to quench heating, which results in a temperature rise across the gap, the remaining 28% goes to ion collisions, thus heating the cathode sheath in a higher power density. The relationships between ion collision heating, quench heating and reduced electric field are given as two functions, which indicates that 10 13  W m −3 is the peak magnitude of power density produced by ion collisions in the nanosecond-pulsed DBD under atmospheric pressure, and a further increase in E/N does not increase the higher quench heating power. The steepness of the negative slope mainly affects the energy transfer efficiency, and the percentage of two heating sources in the total heating power. A short pulse will couple positive and negative slopes and provide a higher transient total heating power but lower energy transfer efficiency. By uncoupling the positive slope, steady stage and negative slope, the energy transfer efficiency under a certain voltage amplitude (20 kV in this paper) is found to have a maximum value of 68.5%. Two wave crests of temperature rise near the cathode sheath are observed, one is caused by a positive slope and the other by a negative slope. (paper)

  1. X-ray polarimetry with a conventional gas proportional counter through rise-time analysis

    CERN Document Server

    Hayashida, K; Tsunemi, H; Torii, K; Murakami, H; Ohno, Y; Tamura, K

    1999-01-01

    We have performed an experiment on the signal rise time of a Xe gas proportional counter using a polarized X-ray beam of synchrotron orbital radiation with energies from 10 to 40 keV. When the counter anode is perpendicular to the electric vector of the incident X-ray photons, the average rise time becomes significantly longer than that for the parallel case. This indicates that the conventional gas proportional counters are useful for X-ray polarimetry. The moderate modulation contrast of this rise-time polarimeter (M=0.1 for 10 keV X-rays and M=0.35 for 40 keV X-rays), with capability of the simultaneous measuring X-ray energies and the timing, would be useful for applications in X-ray astronomy and in other fields.

  2. Effect of rising time of rectangular pulse on inactivation of staphylococcus aureus by pulsed electric field

    Science.gov (United States)

    Zhang, Ruobing; Liang, Dapeng; Zheng, Nanchen; Xiao, Jianfu; Mo, Mengbin; Li, Jing

    2013-03-01

    Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.

  3. Effect of rising time of rectangular pulse on inactivation of staphylococcus aureus by pulsed electric field

    International Nuclear Information System (INIS)

    Zhang, Ruobing; Liang, Dapeng; Xiao, Jianfu; Mo, Mengbin; Li, Jing; Zheng, Nanchen

    2013-01-01

    Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.

  4. Should a carbon tax rise or fall over time?

    International Nuclear Information System (INIS)

    Ulph, Alistair; Ulph, David; Pezzey, John

    1991-01-01

    A carbon tax has been proposed as one possible way of reducing the emissions of ''greenhouse gases''. Much of the recent work on carbon taxation has concentrated on analysing the effects of introducing such a tax at a level which would meet certain emission targets at some fixed date. Less attention has been devoted to the time profile of this tax. Yet in securing international agreement on the introduction of a carbon tax it could matter greatly whether what is being proposed is a tax which is initially low but rising, or initially high but falling. We show that in a wide class of cases the optimal time path of the tax will be that it initially rises and then falls as the exhaustion constraint starts to bite. However there are few general conclusions, and much depends on more detailed modelling assumptions on which the scientific evidence gives no firm guidance. (author)

  5. Amorphous Terfenol-D films using nanosecond pulsed laser deposition

    International Nuclear Information System (INIS)

    Ma, James; O'Brien, Daniel T.; Kovar, Desiderio

    2009-01-01

    Thin films of Terfenol-D were produced by nanosecond pulsed laser deposition (PLD) at two fluences. Electron dispersive spectroscopy conducted using scanning electron and transmission electron microscopes showed that the film compositions were similar to that of the PLD target. Contrary to previous assertions that suggested that nanosecond PLD results in crystalline films, X-ray diffraction and transmission electron microscopy analysis showed that the films produced at both fluences were amorphous. Splatters present on the film had similar compositions to the overall film and were also amorphous. Magnetic measurements showed that the films had high saturation magnetization and magnetostriction, similar to high quality films produced using other physical vapor deposition methods.

  6. Hybrid micromachining using a nanosecond pulsed laser and micro EDM

    International Nuclear Information System (INIS)

    Kim, Sanha; Chung, Do Kwan; Shin, Hong Shik; Chu, Chong Nam; Kim, Bo Hyun

    2010-01-01

    Micro electrical discharge machining (micro EDM) is a well-known precise machining process that achieves micro structures of excellent quality for any conductive material. However, the slow machining speed and high tool wear are main drawbacks of this process. Though the use of deionized water instead of kerosene as a dielectric fluid can reduce the tool wear and increase the machine speed, the material removal rate (MRR) is still low. In contrast, laser ablation using a nanosecond pulsed laser is a fast and non-wear machining process but achieves micro figures of rather low quality. Therefore, the integration of these two processes can overcome the respective disadvantages. This paper reports a hybrid process of a nanosecond pulsed laser and micro EDM for micromachining. A novel hybrid micromachining system that combines the two discrete machining processes is introduced. Then, the feasibility and characteristics of the hybrid machining process are investigated compared to conventional EDM and laser ablation. It is verified experimentally that the machining time can be effectively reduced in both EDM drilling and milling by rapid laser pre-machining prior to micro EDM. Finally, some examples of complicated 3D micro structures fabricated by the hybrid process are shown

  7. Insight into electronic mechanisms of nanosecond-laser ablation of silicon

    International Nuclear Information System (INIS)

    Marine, Wladimir; Patrone, Lionel; Ozerov, Igor; Bulgakova, Nadezhda M.

    2008-01-01

    We present experimental and theoretical studies of nanosecond ArF excimer laser desorption and ablation of silicon with insight into material removal mechanisms. The experimental studies involve a comprehensive analysis of the laser-induced plume dynamics and measurements of the charge gained by the target during irradiation time. At low laser fluences, well below the melting threshold, high-energy ions with a narrow energy distribution are observed. When the fluence is increased, a thermal component of the plume is formed superimposing on the nonthermal ions, which are still abundant. The origin of these ions is discussed on the basis of two modeling approaches, thermal and electronic, and we analyze the dynamics of silicon target excitation, heating, melting, and ablation. An electronic model is developed that provides insight into the charge-carrier transport in the target. We demonstrate that, contrary to a commonly accepted opinion, a complete thermalization between the electron and lattice subsystems is not reached during the nanosecond-laser pulse action. Moreover, the charging effects can retard the melting process and have an effect on the overall target behavior and laser-induced plume dynamics

  8. Influence of the Gilbert damping constant on the flux rise time of write head fields

    International Nuclear Information System (INIS)

    Ertl, Othmar; Schrefl, Thomas; Suess, Dieter; Schabes, Manfred E.

    2005-01-01

    Magnetic recording at fast data rates requires write heads with rapid rise times of the magnetic flux during the write process. We present three-dimensional (3D) micromagnetic finite element calculations of an entire ring head including 3D coil geometry during the writing of magnetic bits in granular media. The simulations demonstrate how input current profiles translate into magnetization processes in the head and which in turn generate the write head field. The flux rise time significantly depends on the Gilbert damping constant of the head material. Low damping causes incoherent magnetization processes, leading to long rise times and low head fields. High damping leads to coherent reversal of the magnetization in the head. As a consequence, the gap region can be quickly saturated which causes high head fields with short rise times

  9. Diffuse mode and diffuse-to-filamentary transition in a high pressure nanosecond scale corona discharge under high voltage

    International Nuclear Information System (INIS)

    Tardiveau, P; Moreau, N; Bentaleb, S; Postel, C; Pasquiers, S

    2009-01-01

    The dynamics of a point-to-plane corona discharge induced in high pressure air under nanosecond scale high overvoltage is investigated. The electrical and optical properties of the discharge can be described in space and time with fast and precise current measurements coupled to gated and intensified imaging. Under atmospheric pressure, the discharge exhibits a diffuse pattern like a multielectron avalanche propagating through a direct field ionization mechanism. The diffuse regime can exist since the voltage rise time is much shorter than the characteristic time of the field screening effects, and as long as the local field is higher than the critical ionization field in air. As one of these conditions is not fulfilled, the discharge turns into a multi-channel regime and the diffuse-to-filamentary transition strongly depends on the overvoltage, the point-to-plane gap length and the pressure. When pressure is increased above atmospheric pressure, the diffuse stage and its transition to streamers seem to satisfy similarity rules as the key parameter is the reduced critical ionization field only. However, above 3 bar, neither diffuse avalanche nor streamer filaments are observed but a kind of streamer-leader regime, due to the fact that mechanisms such as photoionization and heat diffusion are not similar to pressure.

  10. Multiply ionization of diethyl ether clusters by 532 nm nanosecond laser: The influence of laser intensity and the electron energy distribution

    International Nuclear Information System (INIS)

    Zhang Nazhen; Wang Weiguo; Zhao Wuduo; Han Fenglei; Li Haiyang

    2010-01-01

    Graphical abstract: The formation mechanism for multiply charged ions (C q+ and O q+ (q = 2-4)) were investigated experimentally and theoretically using a dual polarity time-of-flight mass spectrometer when diethyl ether clusters interacted with nanosecond laser pulse. - Abstract: The formation mechanism for multiply charged ions (C q+ and O q+ (q = 2-4)) were investigated using a dual polarity time-of-flight mass spectrometer when diethyl ether clusters interacted with nanosecond laser pulse. The signal intensity of multiply charged ions and electron energy was measured experimentally. It was shown that the intensity of multiply charged ions increased about 50 times when laser intensity increased from 7.6 x 10 9 to 7.0 x 10 10 W/cm 2 , then saturated as laser intensity increased further. It is interesting that the evolution of the mean value of electron energy was same to that of multiply charged ions. The theoretical calculation showed the ionization potential of atomic ions could be significantly decreased due to the effect of Coulomb screening especially at low laser intensity. It indicated that the electron ionization combined with Coulomb screening effect could explain the production of multiply charged ions in nanosecond laser field.

  11. Wind tunnel experiments on flow separation control of an Unmanned Air Vehicle by nanosecond discharge plasma aerodynamic actuation

    International Nuclear Information System (INIS)

    Chen Kang; Liang Hua

    2016-01-01

    Plasma flow control (PFC) is a new kind of active flow control technology, which can improve the aerodynamic performances of aircrafts remarkably. The flow separation control of an unmanned air vehicle (UAV) by nanosecond discharge plasma aerodynamic actuation (NDPAA) is investigated experimentally in this paper. Experimental results show that the applied voltages for both the nanosecond discharge and the millisecond discharge are nearly the same, but the current for nanosecond discharge (30 A) is much bigger than that for millisecond discharge (0.1 A). The flow field induced by the NDPAA is similar to a shock wave upward, and has a maximal velocity of less than 0.5 m/s. Fast heating effect for nanosecond discharge induces shock waves in the quiescent air. The lasting time of the shock waves is about 80 μs and its spread velocity is nearly 380 m/s. By using the NDPAA, the flow separation on the suction side of the UAV can be totally suppressed and the critical stall angle of attack increases from 20° to 27° with a maximal lift coefficient increment of 11.24%. The flow separation can be suppressed when the discharge voltage is larger than the threshold value, and the optimum operation frequency for the NDPAA is the one which makes the Strouhal number equal one. The NDPAA is more effective than the millisecond discharge plasma aerodynamic actuation (MDPAA) in boundary layer flow control. The main mechanism for nanosecond discharge is shock effect. Shock effect is more effective in flow control than momentum effect in high speed flow control. (paper)

  12. Fast time-resolved electrostatic force microscopy: Achieving sub-cycle time resolution

    Energy Technology Data Exchange (ETDEWEB)

    Karatay, Durmus U.; Harrison, Jeffrey S.; Glaz, Micah S.; Giridharagopal, Rajiv; Ginger, David S., E-mail: ginger@chem.washington.edu [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States)

    2016-05-15

    The ability to measure microsecond- and nanosecond-scale local dynamics below the diffraction limit with widely available atomic force microscopy hardware would enable new scientific studies in fields ranging from biology to semiconductor physics. However, commercially available scanning-probe instruments typically offer the ability to measure dynamics only on time scales of milliseconds to seconds. Here, we describe in detail the implementation of fast time-resolved electrostatic force microscopy using an oscillating cantilever as a means to measure fast local dynamics following a perturbation to a sample. We show how the phase of the oscillating cantilever relative to the perturbation event is critical to achieving reliable sub-cycle time resolution. We explore how noise affects the achievable time resolution and present empirical guidelines for reducing noise and optimizing experimental parameters. Specifically, we show that reducing the noise on the cantilever by using photothermal excitation instead of piezoacoustic excitation further improves time resolution. We demonstrate the discrimination of signal rise times with time constants as fast as 10 ns, and simultaneous data acquisition and analysis for dramatically improved image acquisition times.

  13. A trial of ignition innovation of gasoline engine by nanosecond pulsed low temperature plasma ignition

    International Nuclear Information System (INIS)

    Shiraishi, Taisuke; Urushihara, Tomonori; Gundersen, Martin

    2009-01-01

    Application of nanosecond pulsed low temperature plasma as an ignition technique for automotive gasoline engines, which require a discharge under conditions of high back pressure, has been studied experimentally using a single-cylinder engine. The nanosecond pulsed plasma refers to the transient (non-equilibrated) phase of a plasma before the formation of an arc discharge; it was obtained by applying a high voltage with a nanosecond pulse (FWHM of approximately 80 or 25 ns) between coaxial cylindrical electrodes. It was confirmed that nanosecond pulsed plasma can form a volumetric multi-channel streamer discharge at an energy consumption of 60 mJ cycle -1 under a high back pressure of 1400 kPa. It was found that the initial combustion period was shortened compared with the conventional spark ignition. The initial flame visualization suggested that the nanosecond pulsed plasma ignition results in the formation of a spatially dispersed initial flame kernel at a position of high electric field strength around the central electrode. It was observed that the electric field strength in the air gap between the coaxial cylindrical electrodes was increased further by applying a shorter pulse. It was also clarified that the shorter pulse improved ignitability even further.

  14. A trial of ignition innovation of gasoline engine by nanosecond pulsed low temperature plasma ignition

    Science.gov (United States)

    Shiraishi, Taisuke; Urushihara, Tomonori; Gundersen, Martin

    2009-07-01

    Application of nanosecond pulsed low temperature plasma as an ignition technique for automotive gasoline engines, which require a discharge under conditions of high back pressure, has been studied experimentally using a single-cylinder engine. The nanosecond pulsed plasma refers to the transient (non-equilibrated) phase of a plasma before the formation of an arc discharge; it was obtained by applying a high voltage with a nanosecond pulse (FWHM of approximately 80 or 25 ns) between coaxial cylindrical electrodes. It was confirmed that nanosecond pulsed plasma can form a volumetric multi-channel streamer discharge at an energy consumption of 60 mJ cycle-1 under a high back pressure of 1400 kPa. It was found that the initial combustion period was shortened compared with the conventional spark ignition. The initial flame visualization suggested that the nanosecond pulsed plasma ignition results in the formation of a spatially dispersed initial flame kernel at a position of high electric field strength around the central electrode. It was observed that the electric field strength in the air gap between the coaxial cylindrical electrodes was increased further by applying a shorter pulse. It was also clarified that the shorter pulse improved ignitability even further.

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

    Science.gov (United States)

    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)

  16. Probing the neutrino mass hierarchy with the rise time of a supernova burst

    Science.gov (United States)

    Serpico, Pasquale D.; Chakraborty, Sovan; Fischer, Tobias; Hüdepohl, Lorenz; Janka, Hans-Thomas; Mirizzi, Alessandro

    2012-04-01

    The rise time of a Galactic supernova (SN) ν¯e light curve, observable at a high-statistics experiment such as the Icecube Cherenkov detector, can provide a diagnostic tool for the neutrino mass hierarchy at “large” 1-3 leptonic mixing angle ϑ13. Thanks to the combination of matter suppression of collective effects at early post-bounce times on one hand and the presence of the ordinary Mikheyev-Smirnov-Wolfenstein effect in the outer layers of the SN on the other hand, a sufficiently fast rise time on O(100)ms scale is indicative of an inverted mass hierarchy. We investigate results from an extensive set of stellar core-collapse simulations, providing a first exploration of the astrophysical robustness of these features. We find that for all the models analyzed (sharing the same weak interaction microphysics) the rise times for the same hierarchy are similar not only qualitatively, but also quantitatively, with the signals for the two classes of hierarchies significantly separated. We show via Monte Carlo simulations that the two cases should be distinguishable at IceCube for SNe at a typical Galactic distance 99% of the time. Finally, a preliminary survey seems to show that the faster rise time for inverted hierarchy as compared to normal hierarchy is a qualitatively robust feature predicted by several simulation groups. Since the viability of this signature ultimately depends on the quantitative assessment of theoretical/numerical uncertainties, our results motivate an extensive campaign of comparison of different code predictions at early accretion times with implementation of microphysics of comparable sophistication, including effects such as nucleon recoils in weak interactions.

  17. SPS Injection and Beam Quality for LHC Heavy Ions With 150 ns Kicker Rise Time

    CERN Document Server

    Goddard, Brennan; Ducimetière, Laurent; Kotzian, Gerd; Uythoven, Jan; Velotti, Francesco

    2016-01-01

    As part of the LHC Injectors Upgrade project for LHC heavy ions, the SPS injection kicker system rise time needs reduction below its present 225 ns. One technically challenging option under consideration is the addition of fast Pulse Forming Lines in parallel to the existing Pulse Forming Networks for the 12 kicker magnets MKP-S, targeting a system field rise time of 100 ns. An alternative option is to optimise the system to approach the existing individual magnet field rise time (2-98%) of 150 ns. This would still significantly increase the number of colliding bunches in LHC while minimising the cost and effort of the system upgrade. The observed characteristics of the present system are described, compared to the expected system rise time, together with results of simulations and measurements with 175 and 150 ns injection batch spacing. The expected beam quality at injection into LHC is quantified, with the emittance growth and simulated tail population taking into account expected jitter and synchronisatio...

  18. Characteristics of 2-heptanone decomposition using nanosecond pulsed discharge plasma

    Science.gov (United States)

    Nakase, Yuki; Fukuchi, Yuichi; Wang, Douyan; Namihira, Takao; Akiyama, Hidenori; Kumamoto University Collaboration

    2015-09-01

    Volatile organic compounds (VOC) evaporate at room temperature. VOCs typically consist of toluene, benzene and ethyl acetate, which are used in cosmetics, dry cleaning products and paints. Exposure to elevated levels of VOCs may cause headaches, dizziness and irritation to the eyes, nose, and throat; they may also cause environmental problems such as air pollution, acid rain and photochemical smog. As such, they require prompt removal. Nanosecond pulsed discharge is a kind of non-thermal plasma consisting of a streamer discharge. Several advantages of nanosecond pulsed discharge plasma have been demonstrated by studies of our research group, including low heat loss, highly energetic electron generation, and the production of highly active radicals. These advantages have shown ns pulsed discharge plasma capable of higher energy efficiency for processes, such as air purification, wastewater treatment and ozone generation. In this research, nanosecond pulsed discharge plasma was employed to treat 2-heptanone, which is a volatile organic compound type and presents several harmful effects. Characteristics of treatment dependent on applied voltage, gas flow rate and input energy density were investigated. Furthermore, byproducts generated by treatment were also investigated.

  19. A large capacity time division multiplexed (TDM) laser beam combining technique enabled by nanosecond speed KTN deflector

    Science.gov (United States)

    Yin, Stuart (Shizhuo); Chao, Ju-Hung; Zhu, Wenbin; Chen, Chang-Jiang; Campbell, Adrian; Henry, Michael; Dubinskiy, Mark; Hoffman, Robert C.

    2017-08-01

    In this paper, we present a novel large capacity (a 1000+ channel) time division multiplexing (TDM) laser beam combining technique by harnessing a state-of-the-art nanosecond speed potassium tantalate niobate (KTN) electro-optic (EO) beam deflector as the time division multiplexer. The major advantages of TDM approach are: (1) large multiplexing capability (over 1000 channels), (2) high spatial beam quality (the combined beam has the same spatial profile as the individual beam), (3) high spectral beam quality (the combined beam has the same spectral width as the individual beam, and (4) insensitive to the phase fluctuation of individual laser because of the nature of the incoherent beam combining. The quantitative analyses show that it is possible to achieve over one hundred kW average power, single aperture, single transverse mode solid state and/or fiber laser by pursuing this innovative beam combining method, which represents a major technical advance in the field of high energy lasers. Such kind of 100+ kW average power diffraction limited beam quality lasers can play an important role in a variety of applications such as laser directed energy weapons (DEW) and large-capacity high-speed laser manufacturing, including cutting, welding, and printing.

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

    Science.gov (United States)

    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. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Formation of various types of nanostructures on germanium surface by nanosecond laser pulses

    Science.gov (United States)

    Mikolutskiy, S. I.; Khasaya, R. R.; Khomich, Yu V.; Yamshchikov, V. A.

    2018-03-01

    The paper describes the formation of micro- and nanostructures in different parts of irradiation zone on germanium surface by multiple action of nanosecond pulses of ArF-laser. It proposes a simple method using only one laser beam without any optional devices and masks for surface treatment. Hexa- and pentagonal cells with submicron dimensions along the surface were observed in peripheral zone of irradiation spot by atomic-force microscopy. Nanostructures in the form of bulbs with rounded peaks with lateral sizes of 40-120 nm were obtained in peripheral low-intensity region of the laser spot. Considering experimental data on material processing by nanosecond laser pulses, a classification of five main types of surface reliefs formed by nanosecond laser pulses with energy density near or slightly above ablation threshold was proposed.

  2. Pattern analysis of laser-tattoo interactions for picosecond- and nanosecond-domain 1,064-nm neodymium-doped yttrium-aluminum-garnet lasers in tissue-mimicking phantom.

    Science.gov (United States)

    Ahn, Keun Jae; Zheng, Zhenlong; Kwon, Tae Rin; Kim, Beom Joon; Lee, Hye Sun; Cho, Sung Bin

    2017-05-08

    During laser treatment for tattoo removal, pigment chromophores absorb laser energy, resulting in fragmentation of the ink particles via selective photothermolysis. The present study aimed to outline macroscopic laser-tattoo interactions in tissue-mimicking (TM) phantoms treated with picosecond- and nanosecond-domain lasers. Additionally, high-speed cinematographs were captured to visualize time-dependent tattoo-tissue interactions, from laser irradiation to the formation of photothermal and photoacoustic injury zones (PIZs). In all experimental settings using the nanosecond or picosecond laser, tattoo pigments fragmented into coarse particles after a single laser pulse, and further disintegrated into smaller particles that dispersed toward the boundaries of PIZs after repetitive delivery of laser energy. Particles fractured by picosecond treatment were more evenly dispersed throughout PIZs than those fractured by nanosecond treatment. Additionally, picosecond-then-picosecond laser treatment (5-pass-picosecond treatment + 5-pass-picosecond treatment) induced greater disintegration of tattoo particles within PIZs than picosecond-then-nanosecond laser treatment (5-pass-picosecond treatment + 5-pass-nanosecond treatment). High-speed cinematography recorded the formation of PIZs after repeated reflection and propagation of acoustic waves over hundreds of microseconds to a few milliseconds. The present data may be of use in predicting three-dimensional laser-tattoo interactions and associated reactions in surrounding tissue.

  3. The effects of gaseous bubble composition and gap distance on the characteristics of nanosecond discharges in distilled water

    KAUST Repository

    Hamdan, Ahmad

    2016-05-17

    Electric discharge in liquids with bubbles can reduce the energy consumption, which increases treatment efficiency. We present an experimental study of nanosecond discharges in distilled water bubbled with the monoatomic gas argon and with the polyatomic gases methane, carbon dioxide, and propane. We monitor the time evolution of the voltage and current waveforms, and calculate the injected charges to characterize the discharge. We establish a relationship between the injected charges and the shape of the plasma by time-resolved imaging to find that increasing the size of the gap reduces the injected charges. Moreover, we determine the plasma characteristics, including electron density, excitation temperatures (for atoms and ions), and rotational temperature of the OH and C2 radicals found in the plasma. Our space- and time-averaged measurements allow us to propose a spatial distribution of the plasma that is helpful for understanding the plasma dynamics necessary to develop and optimize applications based on nanosecond discharges in bubbled liquids. © 2016 IOP Publishing Ltd.

  4. Time resolved techniques: An overview

    International Nuclear Information System (INIS)

    Larson, B.C.; Tischler, J.Z.

    1990-06-01

    Synchrotron sources provide exceptional opportunities for carrying out time-resolved x-ray diffraction investigations. The high intensity, high angular resolution, and continuously tunable energy spectrum of synchrotron x-ray beams lend themselves directly to carrying out sophisticated time-resolved x-ray scattering measurements on a wide range of materials and phenomena. When these attributes are coupled with the pulsed time-structure of synchrotron sources, entirely new time-resolved scattering possibilities are opened. Synchrotron beams typically consist of sub-nanosecond pulses of x-rays separated in time by a few tens of nanoseconds to a few hundred nanoseconds so that these beams appear as continuous x-ray sources for investigations of phenomena on time scales ranging from hours down to microseconds. Studies requiring time-resolution ranging from microseconds to fractions of a nanosecond can be carried out in a triggering mode by stimulating the phenomena under investigation in coincidence with the x-ray pulses. Time resolution on the picosecond scale can, in principle, be achieved through the use of streak camera techniques in which the time structure of the individual x-ray pulses are viewed as quasi-continuous sources with ∼100--200 picoseconds duration. Techniques for carrying out time-resolved scattering measurements on time scales varying from picoseconds to kiloseconds at present and proposed synchrotron sources are discussed and examples of time-resolved studies are cited. 17 refs., 8 figs

  5. Microstructured silicon created with a nanosecond neodymium-doped yttrium aluminum garnet laser

    Energy Technology Data Exchange (ETDEWEB)

    Mandeville, W.J. [MITRE Corporation, Colorado Springs, CO (United States); Shaffer, M.K.; Lu, Yalin; O' Keefe, D.; Knize, R.J. [United States Air Force Academy, USAFA, CO (United States)

    2011-08-15

    We produce microstructured silicon using frequency doubled, nanosecond Nd:YAG pulses in SF{sub 6} gas. The micro-penitentes formed are up to 20 {mu}m tall with a sulfur concentration of 0.5% near the surface. The infrared absorption is increased to near unity and extends well below the original bandgap far into the infrared. These data are similar to results reported by others using more complicated and less economical femtosecond titanium sapphire and picosecond and nanosecond excimer lasers. (orig.)

  6. A ‘frozen electric-field’ approach to simulate repetitively pulsed nanosecond plasma discharges and ignition of hydrogen–air mixtures

    International Nuclear Information System (INIS)

    Nagaraja, Sharath; Yang, Vigor

    2014-01-01

    High-fidelity modelling of nanosecond repetitively pulsed discharges (NRPDs) is burdened by the multiple time and length scales and large chemistry mechanisms involved, which prohibit detailed analyses and parametric studies. In the present work, we propose a ‘frozen electric-field’ modelling approach to expedite the NRPD simulations without adverse effects on the solution accuracy. First, a burst of nanosecond voltage pulses is simulated self-consistently until the discharge reaches a stationary state. The calculated spatial distributions and temporal evolution of the electric field, electron density and electron energy during the last pulse are then stored in a library and the electrical characteristics of subsequent pulses are frozen at these values. This strategy allows the timestep for numerical integration to be increased by four orders of magnitude (from 10 −13 to 10 −9  s), thereby significantly improving the computational efficiency of the process. Reduced calculations of a burst of 50 discharge pulses show good agreement with the predictions from a complete plasma model (electrical characteristics calculated during each pulse). The error in species densities is less than 20% at the centre of the discharge volume and about 30% near the boundaries. The deviations in temperature, however, are much lower, at 5% in the entire domain. The model predictions are in excellent agreement with measured ignition delay times and temperatures in H 2 –air mixtures subject to dielectric barrier NRPD over a pressure range of 54–144 Torr with equivalence ratios of 0.7–1.2. The OH density increases with pressure and triggers low-temperature fuel oxidation, which leads to rapid temperature rise and ignition. The ignition delay decreases by a factor of 2, with an increase in pressure from 54 to 144 Torr. In contrast, an increase in the H 2 –air equivalence ratio from 0.7 to 1.2 marginally decreases the ignition delay by about 20%. This behaviour is

  7. Time-resolved imaging of filamentary damage on the exit surface of fused silica induced by 1064 nm nanosecond laser pulse

    International Nuclear Information System (INIS)

    Chao, Shen; Xiang’ai, Cheng; Tian, Jiang; Zhiwu, Zhu; Yifan, Dai

    2015-01-01

    Laser-induced damage on the exit surface of fused silica with a filament was observed. The filament has a central hollow core surrounded by molten materials and no obvious cracks could be observed. The critical intensity for the transition from pure surface damage (SD) to filamentary damage (FD) was measured. Time-resolved shadowgraphic microscopy with nanosecond time resolution was employed to compare the propagation of shock wave and material response in the SD and FD process. The main different features during the material response process include: (i) thermoelastic shock waves launched in FD were multiple and a column envelope was observed in the lateral direction; (ii) more energy is deposited in the bulk for FD resulting to a lower speed of shock wave in air; (iii) the overall time for establishing the main character of the damage site for FD was shorter because of the absence of crack expansion. Self-focusing and temperature-activated optical absorption enhancement of the bulk material are discussed to explain the morphology difference between SD and FD and the evolution of filament length under different incident intensities. (paper)

  8. Measures to reduce construction time of high-rise buildings

    Science.gov (United States)

    Kolchedantsev, Leonid; Adamtsevich, Aleksey; Stupakova, Olga; Drozdov, Alexander

    2018-03-01

    The organizational and technological solutions for high-rise buildings construction efficiency increase are considered, primarily - decrease of typical floor construction time and improvement of bearing structures concrete quality. The essence of offered technology is: a concrete mixing station and a polygon mainly for load-bearing wall panels with starter bars casting are located on the building site; for reinforced concrete components manufacturing and butt joints grouting the warmed-up concrete mixtures are used. The results of researches and elaborations carried out by the SPSUACE in area of a preliminary warming-up of concrete mixtures are presented. The possibility and feasibility of their usage in high-rise buildings and of excess height buildings construction including cast-in-place and precast execution are shown. The essence of heat-vibro treating of concrete mixture is revealed as a kind of prior electroresistive curing, and the achieved results are: accelerated concrete strength gain, power inputs decrease, concrete quality improvement. It is shown that the location of a concrete mixing station on the building site enables to broaden possibilities of the "thermos" method use and to avoid concrete mixtures warming up in medium-mass structures erection (columns, girders) during the high-rise buildings construction. It is experimentally proved that the splice between precast elements encased with warmed-up concrete mixture is equal with conjugated elements in strength.

  9. Amplitude and rise time compensated timing optimized for large semiconductor detectors

    International Nuclear Information System (INIS)

    Kozyczkowski, J.J.; Bialkowski, J.

    1976-01-01

    The ARC timing described has excellent timing properties even when using a wide range e.g. from 10 keV to over 1 MeV. The detector signal from a preamplifier is accepted directly by the unit as a timing filter amplifier with a sensitivity of 1 mV is incorporated. The adjustable rise time rejection feature makes it possible to achieve a good prompt time spectrum with symmetrical exponential shape down to less than 1/100 of the peak value. A complete block diagram of the unit is given together with results of extensive tests of its performance. For example the time spectrum for (1330+-20) keV of 60 Co taken with a 43 cm 3 Ge(Li) detector has the following parameters: fwhm = 2.2ns, fwtm = 4.4 ns and fw (0.01) m = 7.6 ns and for (50 +- 10) keV of 22 Na the following was obtained: fwhm = 10.8 ns, fwtm = 21.6 ns and fw (0.01) m = 34.6 ns. In another experiment with two fast plastic scintillations (NE 102A) and using a 20% dynamic energy range the following was measured: fwhm = 280 ps, fwtm = 470 ps and fw (0.01) m = 70ps. (Auth.)

  10. Ozone and dinitrogen monoxide production in atmospheric pressure air dielectric barrier discharge plasma effluent generated by nanosecond pulse superimposed alternating current voltage

    Science.gov (United States)

    Takashima, Keisuke; Kaneko, Toshiro

    2017-06-01

    The effects of nanosecond pulse superposition to alternating current voltage (NS + AC) on the generation of an air dielectric barrier discharge (DBD) plasma and reactive species are experimentally studied, along with measurements of ozone (O3) and dinitrogen monoxide (N2O) in the exhausted gas through the air DBD plasma (air plasma effluent). The charge-voltage cycle measurement indicates that the role of nanosecond pulse superposition is to induce electrical charge transport and excess charge accumulation on the dielectric surface following the nanosecond pulses. The densities of O3 and N2O in NS + AC DBD are found to be significantly increased in the plasma effluent, compared to the sum of those densities generated in NS DBD and AC DBD operated individually. The production of O3 and N2O is modulated significantly by the phase in which the nanosecond pulse is superimposed. The density increase and modulation effects by the nanosecond pulse are found to correspond with the electrical charge transport and the excess electrical charge accumulation induced by the nanosecond pulse. It is suggested that the electrical charge transport by the nanosecond pulse might result in the enhancement of the nanosecond pulse current, which may lead to more efficient molecular dissociation, and the excess electrical charge accumulation induced by the nanosecond pulse increases the discharge coupling power which would enhance molecular dissociation.

  11. Decomposition of three volatile organic compounds by nanosecond pulsed corona discharge: Study of by-product formation and influence of high voltage pulse parameters

    Science.gov (United States)

    Jarrige, Julien; Vervisch, Pierre

    2006-06-01

    Increasing concerns over atmospheric pollution has motivated research into technologies able to remove volatile organic compounds (VOC's) from gas streams. The aim of this paper is to understand the chemical and physical mechanisms implied in the decomposition of VOC's in a filamentary nonthermal plasma discharge. Experiments have been carried out on three pollutants (propane, propene, and isopropyl alcohol) in dry air at atmospheric pressure using a wire to cylinder corona discharge generated by a homemade nanosecond rise time high voltage pulse generator. The resulting plasma efficiently destructs propane, propene, or isopropyl alcohol at a concentration of 500 ppm with low specific input energies (less than 500 J/L), but the poor oxidation rate leads to the formation of numerous by-products (acetone, formaldehyde, formic acid, and methyl nitrate) whose concentration can reach some hundreds of ppm. We also investigated the effect of pulse parameters on VOC removal efficiency. Neither pulse peak value nor rise time (in the range of 4-12 ns) appears to have a significant influence on the VOC decomposition rates. Therefore, we believe that the way the energy is deposited in the plasma does not modify the density of active species (radicals, ions) in the streamers. The production of energetic electrons is not enhanced by the external applied field, and the only effective parameter may be the local field in the streamer head, which is almost the same (around 500 Td) whatever the voltage (above the inception value).

  12. Decomposition of three volatile organic compounds by nanosecond pulsed corona discharge: Study of by-product formation and influence of high voltage pulse parameters

    International Nuclear Information System (INIS)

    Jarrige, Julien; Vervisch, Pierre

    2006-01-01

    Increasing concerns over atmospheric pollution has motivated research into technologies able to remove volatile organic compounds (VOC's) from gas streams. The aim of this paper is to understand the chemical and physical mechanisms implied in the decomposition of VOC's in a filamentary nonthermal plasma discharge. Experiments have been carried out on three pollutants (propane, propene, and isopropyl alcohol) in dry air at atmospheric pressure using a wire to cylinder corona discharge generated by a homemade nanosecond rise time high voltage pulse generator. The resulting plasma efficiently destructs propane, propene, or isopropyl alcohol at a concentration of 500 ppm with low specific input energies (less than 500 J/L), but the poor oxidation rate leads to the formation of numerous by-products (acetone, formaldehyde, formic acid, and methyl nitrate) whose concentration can reach some hundreds of ppm. We also investigated the effect of pulse parameters on VOC removal efficiency. Neither pulse peak value nor rise time (in the range of 4-12 ns) appears to have a significant influence on the VOC decomposition rates. Therefore, we believe that the way the energy is deposited in the plasma does not modify the density of active species (radicals, ions) in the streamers. The production of energetic electrons is not enhanced by the external applied field, and the only effective parameter may be the local field in the streamer head, which is almost the same (around 500 Td) whatever the voltage (above the inception value)

  13. A distributed parameter model of transmission line transformer for high voltage nanosecond pulse generation.

    Science.gov (United States)

    Li, Jiangtao; Zhao, Zheng; Li, Longjie; He, Jiaxin; Li, Chenjie; Wang, Yifeng; Su, Can

    2017-09-01

    A transmission line transformer has potential advantages for nanosecond pulse generation including excellent frequency response and no leakage inductance. The wave propagation process in a secondary mode line is indispensable due to an obvious inside transient electromagnetic transition in this scenario. The equivalent model of the transmission line transformer is crucial for predicting the output waveform and evaluating the effects of magnetic cores on output performance. However, traditional lumped parameter models are not sufficient for nanosecond pulse generation due to the natural neglect of wave propagations in secondary mode lines based on a lumped parameter assumption. In this paper, a distributed parameter model of transmission line transformer was established to investigate wave propagation in the secondary mode line and its influential factors through theoretical analysis and experimental verification. The wave propagation discontinuity in the secondary mode line induced by magnetic cores is emphasized. Characteristics of the magnetic core under a nanosecond pulse were obtained by experiments. Distribution and formation of the secondary mode current were determined for revealing essential wave propagation processes in secondary mode lines. The output waveform and efficiency were found to be affected dramatically by wave propagation discontinuity in secondary mode lines induced by magnetic cores. The proposed distributed parameter model was proved more suitable for nanosecond pulse generation in aspects of secondary mode current, output efficiency, and output waveform. In depth, comprehension of underlying mechanisms and a broader view of the working principle of the transmission line transformer for nanosecond pulse generation can be obtained through this research.

  14. Single-label kinase and phosphatase assays for tyrosine phosphorylation using nanosecond time-resolved fluorescence detection.

    Science.gov (United States)

    Sahoo, Harekrushna; Hennig, Andreas; Florea, Mara; Roth, Doris; Enderle, Thilo; Nau, Werner M

    2007-12-26

    The collision-induced fluorescence quenching of a 2,3-diazabicyclo[2.2.2]oct-2-ene-labeled asparagine (Dbo) by hydrogen atom abstraction from the tyrosine residue in peptide substrates was introduced as a single-labeling strategy to assay the activity of tyrosine kinases and phosphatases. The assays were tested for 12 different combinations of Dbo-labeled substrates and with the enzymes p60c-Src Src kinase, EGFR kinase, YOP protein tyrosine phosphatase, as well as acid and alkaline phosphatases, thereby demonstrating a broad application potential. The steady-state fluorescence changed by a factor of up to 7 in the course of the enzymatic reaction, which allowed for a sufficient sensitivity of continuous monitoring in steady-state experiments. The fluorescence lifetimes (and intensities) were found to be rather constant for the phosphotyrosine peptides (ca. 300 ns in aerated water), while those of the unphosphorylated peptides were as short as 40 ns (at pH 7) and 7 ns (at pH 13) as a result of intramolecular quenching. Owing to the exceptionally long fluorescence lifetime of Dbo, the assays were alternatively performed by using nanosecond time-resolved fluorescence (Nano-TRF) detection, which leads to an improved discrimination of background fluorescence and an increased sensitivity. The potential for inhibitor screening was demonstrated through the inhibition of acid and alkaline phosphatases by molybdate.

  15. Large-volume excitation of air, argon, nitrogen and combustible mixtures by thermal jets produced by nanosecond spark discharges

    Science.gov (United States)

    Stepanyan, Sergey; Hayashi, Jun; Salmon, Arthur; Stancu, Gabi D.; Laux, Christophe O.

    2017-04-01

    This work presents experimental observations of strong expanding thermal jets following the application of nanosecond spark discharges. These jets propagate in a toroidal shape perpendicular to the interelectrode axis, with high velocities of up to 30 m s-1 and over distances of the order of a cm. Their propagation length is much larger than the thermal expansion region produced by the conventional millisecond sparks used in car engine ignition, thus greatly improving the volumetric excitation of gas mixtures. The shape and velocity of the jets is found to be fairly insensitive to the shape of the electrodes. In addition, their spatial extent is found to increase with the number of nanosecond sparks and with the discharge voltage, and to decrease slightly with the pressure between 1 and 7 atm at constant applied voltage. Finally, this thermal jet phenomenon is observed in experiments conducted with many types of gas mixtures, including air, nitrogen, argon, and combustible CH4/air mixtures. This makes nanosecond repetitively pulsed discharges particularly attractive for aerodynamic flow control or plasma-assisted combustion because of their ability to excite large volumes of gas, typically about 100 times the volume of the discharge.

  16. AN INDUCTION SENSOR FOR MEASURING CURRENTS OF NANOSECOND RANGE

    Directory of Open Access Journals (Sweden)

    S. P. Shalamov

    2016-11-01

    Full Text Available Purpose. A current meter based on the principle of electromagnetic induction is designed to register the current flowing in the rod lightning. The aim of the article is to describe the way of increasing the sensitivity of the converter by means of their serial communication. Methodology. The recorded current is in the nanosecond range. If compared with other methods, meters based on the principle of electromagnetic induction have several advantages, such as simplicity of construction, reliability, low cost, no need in a power source, relatively high sensitivity. Creation of such a meter is necessary, because in some cases there is no possibility to use a shunt. Transient properties of a meter are determined by the number of turns and the constant of integration. Sensitivity is determined by measuring the number of turns, the coil sectional area, the core material and the integration constant. For measuring the magnetic field pulses with a rise time of 5 ns to 50 ns a meter has turns from 5 to 15. The sensitivity of such a meter is low. When the number of turns is increased, the output signal and the front increase. Earlier described dependencies were used to select the main parameters of the converter. It was based on generally accepted and widely known equivalent circuit. The experience of created earlier pulse magnetic field meters was considered both for measuring the magnetic fields, and large pulse current. Originality. Series connection of converters has the property of a long line. The level of the transient response of the meter is calculated. The influence of parasitic parameters on the type of meter transient response is examined. The shown construction was not previously described. Practical value. The results of meter implementation are given. The design peculiarities of the given measuring instruments are shown.

  17. Dynamic of ozone formation in nanosecond microwave discharges

    International Nuclear Information System (INIS)

    Akhmedzhanov, R.A.; Vikharev, A.L.; Gorbachev, A.M.

    1995-01-01

    Nanosecond gas discharges are efficient sources of chemically active plasma. Studies of the nanosecond microwave discharge are interesting for remote modification of the chemical composition of the atmosphere in term of its purification, for diagnostics of impurities and ozone replenishment in the regions of local open-quotes ozone holesclose quotes. In this connection a study of plasma chemical processes in such a discharge seems appropriate, as well as modeling of ecological consequences of the effect of powerful microwave radiation on the atmosphere. The present paper contains generalized results of studying the process of ozone formation in a pulse-periodic freely localized nanosecond microwave discharge. The experiments were performed in a wide range of parameters: microwave radiation wavelength λ = 0.8 and 3cm, pulse duration τ = 6 and 500ns, pulse power P = 50kW and 20MW, pulse repetition rate F = 1-10 3 Hz. The working gases were air and oxygen under pressure P = 10-100Torr. As a source of the microwave radiation a pulse magnetron was used with a device for pulse compression based on the waveguide resonator, and a relativistic microwave generator. The discharge was produced in the focus of the parabolic mirror and had the form of homogeneous cylinder. The plasma chemical processes were studied in two cases. The discharge was created either in the quartz tube placed along the focal line of the mirror or in the free air. Dynamics of formation of ozone and nitrogen oxides in the discharge was studied by means of absorption spectroscopy in the regime of accumulation of the products of chemical reactions (in a closed volume) and their diffusion spreading

  18. Dynamical propagation of nanosecond pulses in Naphthalocyanines and Phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Quan, E-mail: qmiao2013@yahoo.com [College of Electronics, Communication and Physics, Shandong University of Science and Technology, Qingdao 266590, Shandong (China); Liang, Min; Liu, Qixin [College of Electronics, Communication and Physics, Shandong University of Science and Technology, Qingdao 266590, Shandong (China); College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590, Shandong (China); Wang, Jing-Jing [College of Electronics, Communication and Physics, Shandong University of Science and Technology, Qingdao 266590, Shandong (China); Sun, Erping; Xu, Yan [College of Electronics, Communication and Physics, Shandong University of Science and Technology, Qingdao 266590, Shandong (China); College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590, Shandong (China)

    2016-11-30

    Highlights: • We study the dynamical processes of nanoseconds lasers in Naphthalocyanines and Phthalocyanines. • We provide theoretical evidences of the main mechanism of optical power limiting. • The central metals play more important roles in the dynamical processes. • The main reason is the central metals enhance the spin–orbit coupling. - Abstract: Dynamical propagation and optical limiting of nanosecond pulses in peripherally substituted Naphthalocyanines (Npcs) and Phthalocyanines (Pcs) with central metals gallium and indium were theoretically studied using paraxial field and rate equations. The results demonstrated that both Npcs and Pcs have good optical limiting performances, and Npc with heavier central mental indium shows better optical limiting properities due to the stronger reverse saturable absorption, which is mainly strengthened by the larger one-photo absorption cross section of excited state and the faster intersystem crossing rate.

  19. Nanosecond electric pulses trigger actin responses in plant cells

    International Nuclear Information System (INIS)

    Berghoefer, Thomas; Eing, Christian; Flickinger, Bianca; Hohenberger, Petra; Wegner, Lars H.; Frey, Wolfgang; Nick, Peter

    2009-01-01

    We have analyzed the cellular effects of nanosecond pulsed electrical fields on plant cells using fluorescently tagged marker lines in the tobacco cell line BY-2 and confocal laser scanning microscopy. We observe a disintegration of the cytoskeleton in the cell cortex, followed by contraction of actin filaments towards the nucleus, and disintegration of the nuclear envelope. These responses are accompanied by irreversible permeabilization of the plasma membrane manifest as uptake of Trypan Blue. By pretreatment with the actin-stabilizing drug phalloidin, the detachment of transvacuolar actin from the cell periphery can be suppressed, and this treatment can also suppress the irreversible perforation of the plasma membrane. We discuss these findings in terms of a model, where nanosecond pulsed electric fields trigger actin responses that are key events in the plant-specific form of programmed cell death.

  20. Timed Rise from Floor as a Predictor of Disease Progression in Duchenne Muscular Dystrophy: An Observational Study.

    Directory of Open Access Journals (Sweden)

    Elena S Mazzone

    Full Text Available The role of timed items, and more specifically, of the time to rise from the floor, has been reported as an early prognostic factor for disease progression and loss of ambulation. The aim of our study was to investigate the possible effect of the time to rise from the floor test on the changes observed on the 6MWT over 12 months in a cohort of ambulant Duchenne boys.A total of 487 12-month data points were collected from 215 ambulant Duchenne boys. The age ranged between 5.0 and 20.0 years (mean 8.48 ±2.48 DS.The results of the time to rise from the floor at baseline ranged from 1.2 to 29.4 seconds in the boys who could perform the test. 49 patients were unable to perform the test at baseline and 87 at 12 month The 6MWT values ranged from 82 to 567 meters at baseline. 3 patients lost the ability to perform the 6mwt at 12 months. The correlation between time to rise from the floor and 6MWT at baseline was high (r = 0.6, p<0.01.Both time to rise from the floor and baseline 6MWT were relevant for predicting 6MWT changes in the group above the age of 7 years, with no interaction between the two measures, as the impact of time to rise from the floor on 6MWT change was similar in the patients below and above 350 m. Our results suggest that, time to rise from the floor can be considered an additional important prognostic factor of 12 month changes on the 6MWT and, more generally, of disease progression.

  1. Nanosecond laser textured superhydrophobic metallic surfaces and their chemical sensing applications

    Science.gov (United States)

    Ta, Duong V.; Dunn, Andrew; Wasley, Thomas J.; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Connaughton, Colm; Shephard, Jonathan D.

    2015-12-01

    This work demonstrates superhydrophobic behavior on nanosecond laser patterned copper and brass surfaces. Compared with ultrafast laser systems previously used for such texturing, infrared nanosecond fiber lasers offer a lower cost and more robust system combined with potentially much higher processing rates. The wettability of the textured surfaces develops from hydrophilicity to superhydrophobicity over time when exposed to ambient conditions. The change in the wetting property is attributed to the partial deoxidation of oxides on the surface induced during laser texturing. Textures exhibiting steady state contact angles of up to ∼152° with contact angle hysteresis of around 3-4° have been achieved. Interestingly, the superhydrobobic surfaces have the self-cleaning ability and have potential for chemical sensing applications. The principle of these novel chemical sensors is based on the change in contact angle with the concentration of methanol in a solution. To demonstrate the principle of operation of such a sensor, it is found that the contact angle of methanol solution on the superhydrophobic surfaces exponentially decays with increasing concentration. A significant reduction, of 128°, in contact angle on superhydrophobic brass is observed, which is one order of magnitude greater than that for the untreated surface (12°), when percent composition of methanol reaches to 28%.

  2. Sea-level rise and shoreline retreat: time to abandon the Bruun Rule

    Science.gov (United States)

    Cooper, J. Andrew G.; Pilkey, Orrin H.

    2004-11-01

    In the face of a global rise in sea level, understanding the response of the shoreline to changes in sea level is a critical scientific goal to inform policy makers and managers. A body of scientific information exists that illustrates both the complexity of the linkages between sea-level rise and shoreline response, and the comparative lack of understanding of these linkages. In spite of the lack of understanding, many appraisals have been undertaken that employ a concept known as the "Bruun Rule". This is a simple two-dimensional model of shoreline response to rising sea level. The model has seen near global application since its original formulation in 1954. The concept provided an advance in understanding of the coastal system at the time of its first publication. It has, however, been superseded by numerous subsequent findings and is now invalid. Several assumptions behind the Bruun Rule are known to be false and nowhere has the Bruun Rule been adequately proven; on the contrary several studies disprove it in the field. No universally applicable model of shoreline retreat under sea-level rise has yet been developed. Despite this, the Bruun Rule is in widespread contemporary use at a global scale both as a management tool and as a scientific concept. The persistence of this concept beyond its original assumption base is attributed to the following factors: Appeal of a simple, easy to use analytical model that is in widespread use. Difficulty of determining the relative validity of 'proofs' and 'disproofs'. Ease of application. Positive advocacy by some scientists. Application by other scientists without critical appraisal. The simple numerical expression of the model. Lack of easy alternatives. The Bruun Rule has no power for predicting shoreline behaviour under rising sea level and should be abandoned. It is a concept whose time has passed. The belief by policy makers that it offers a prediction of future shoreline position may well have stifled much

  3. Fast switching thyristor applied in nanosecond-pulse high-voltage generator with closed transformer core.

    Science.gov (United States)

    Li, Lee; Bao, Chaobing; Feng, Xibo; Liu, Yunlong; Fochan, Lin

    2013-02-01

    For a compact and reliable nanosecond-pulse high-voltage generator (NPHVG), the specification parameter selection and potential usage of fast controllable state-solid switches have an important bearing on the optimal design. The NPHVG with closed transformer core and fast switching thyristor (FST) was studied in this paper. According to the analysis of T-type circuit, the expressions for the voltages and currents of the primary and secondary windings on the transformer core of NPHVG were deduced, and the theoretical maximum analysis was performed. For NPHVG, the rise-rate of turn-on current (di/dt) across a FST may exceed its transient rating. Both mean and maximum values of di/dt were determined by the leakage inductances of the transformer, and the difference is 1.57 times. The optimum winding ratio is helpful to getting higher voltage output with lower specification FST, especially when the primary and secondary capacitances have been established. The oscillation period analysis can be effectively used to estimate the equivalent leakage inductance. When the core saturation effect was considered, the maximum di/dt estimated from the oscillating period of the primary current is more accurate than one from the oscillating period of the secondary voltage. Although increasing the leakage inductance of NPHVG can decrease di/dt across FST, it may reduce the output peak voltage of the NPHVG.

  4. Design of a ns-pulse generator with microwave studio

    NARCIS (Netherlands)

    Huiskamp, T.; Voeten, S.J.; Pemen, A.J.M.

    2012-01-01

    In this paper we present a design approach of a nanosecond pulse generator by using CST MICROWAVE STUDIO R . Through detailed simulation we arrive at a design for a fast rise-time variable pulse duration pulse generator which is able to produce 1–10 nanosecond pulses with tens of kilovolt amplitude.

  5. Neutron spectrum measurement using rise-time discrimination method

    International Nuclear Information System (INIS)

    Luo Zhiping; Suzuki, C.; Kosako, T.; Ma Jizeng

    2009-01-01

    PSD method can be used to measure the fast neutron spectrum in n/γ mixed field. A set of assemblies for measuring the pulse height distribution of neutrons is built up,based on a large volume NE213 liquid scintillator and standard NIM circuits,through the rise-time discrimination method. After that,the response matrix is calculated using Monte Carlo method. The energy calibration of the pulse height distribution is accomplished using 60 Co radioisotope. The neutron spectrum of the mono-energetic accelerator neutron source is achieved by unfolding process. Suggestions for further improvement of the system are presented at last. (authors)

  6. Modular High Voltage Pulse Converter for Short Rise and Decay Times

    NARCIS (Netherlands)

    Mao, S.

    2018-01-01

    This thesis explores a modular HV pulse converter technology with short rise and decay times. A systematic methodology to derive and classify HV architectures based on a modularization level of power building blocks of the HV pulse converter is developed to summarize existing architectures and

  7. Pixel readout ASIC for an APD based 2D X-ray hybrid pixel detector with sub-nanosecond resolution

    Energy Technology Data Exchange (ETDEWEB)

    Thil, Ch., E-mail: christophe.thil@ziti.uni-heidelberg.d [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Baron, A.Q.R. [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Fajardo, P. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France); Fischer, P. [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Graafsma, H. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Rueffer, R. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France)

    2011-02-01

    The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 x32 pixels covering about 1 cm{sup 2} active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of 280{mu}mx280{mu}m size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4x4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed.

  8. Pixel readout ASIC for an APD based 2D X-ray hybrid pixel detector with sub-nanosecond resolution

    International Nuclear Information System (INIS)

    Thil, Ch.; Baron, A.Q.R.; Fajardo, P.; Fischer, P.; Graafsma, H.; Rueffer, R.

    2011-01-01

    The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 x32 pixels covering about 1 cm 2 active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of 280μmx280μm size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4x4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed.

  9. Stability of high current diode under 100-nanosecond-pulse voltage

    International Nuclear Information System (INIS)

    Lai Dingguo; Qiu Aici; Zhang Yongmin; Huang Jianjun; Ren Shuqing; Yang Li

    2012-01-01

    Stability of high current diode under pulse voltage with 80 ns and 34 ns rise time was studied on the flash Ⅱ accelerator. Influence of rise time of diode voltage on startup time and cathode emission uniformity and repeatability of diode impedance was analyzed by comparing the experimental results with numerically simulated results, and the influence mechanism was discussed. The startup time of diode increases with the increasing of rise time of voltage, and the repeatability of diode impedance decreases. Discal plane cathode is prone to emit rays intensely in the center area, the time that plasma covers the surface of the cathode increases and the shielding effect has more impact on cathode emission according to the increase of rise time. Local intense emission on the cathode increases expansion speed of plasma and reduces the effective emission area. The stability of characteristic impedance of diode under a pulse voltage with slow rise time is decreased by the combined action of expansion speed of plasma and the effective emission area. (authors)

  10. Nanosecond (ns) laser transfer of silver nanoparticles from silver-exchanged soda-lime glass to transparent soda-lime glass and shock waves formation

    International Nuclear Information System (INIS)

    Sow, Mohamed Chérif; Blondeau, Jean-Philippe; Sagot, Nadine; Ollier, Nadège; Tite, Teddy

    2015-01-01

    Highlights: • Silver nanoparticles growth by nanosecond laser irradiation of silver exchanged soda-lime glasses. • Silver nanoparticles transfer. • Nanosecond laser induced shock waves formation on glass. - Abstract: In this contribution, we showed for the first time in our knowledge a single-step process for silver clusters and nanoparticles growth and transfer from silver-exchanged soda-lime glass to un-exchanged soda-lime glass (transparent glass in visible and NIR domain) by nanosecond (ns) laser irradiation. The transferred silver nanoparticles in transparent glass are strongly linked to the glass surface. In addition, we point out the formation of shock waves, with selective silver clustering on the top wave. This technique provides an alternative and simple way to obtain metallic nanoparticles in different media which can be traversed by laser wavelength used. Moreover, this experiment is made at room temperature and air environment. It is worth noting that our technique requires a glass previously doped with the corresponding silver ions

  11. Experimental study of mechanical response of artificial tissue models irradiated with Nd:YAG nanosecond laser pulses

    Science.gov (United States)

    Pérez-Gutiérrez, Francisco G.; Camacho-López, Santiago; Aguilar, Guillermo

    2011-07-01

    Nanosecond long laser pulses are used in medical applications where precise tissue ablation with minimal thermal and mechanical collateral damage is required. When a laser pulse is incident on a material, optical energy will be absorbed by a combination of linear and nonlinear absorption according to both: laser light irradiance and material properties. In the case of water or gels, the first results in heat generation and thermoelastic expansion; while the second results in an expanding plasma formation that launches a shock wave and a cavitation/boiling bubble. Plasma formation due to nonlinear absorption of nanosecond laser pulses is originated by a combination of multiphoton ionization and thermionic emission of free electrons, which is enhanced when the material has high linear absorption coefficient. In this work, we present three experimental approaches to study pressure transients originated when 6 ns laser pulses are incident on agar gels and water with varying linear absorption coefficient, using laser radiant exposures above and below threshold for bubble formation: (a) PVDF sensors, (b) Time-resolved shadowgraphy and (c) Time-resolved interferometry. The underlying hypothesis is that pressure transients are composed of the superposition of both: shock wave originated by hot expanding plasma resulting from nonlinear absorption of optical energy and, thermoelastic expansion originated by heat generation due to linear absorption of optical energy. The objective of this study is to carry out a comprehensive experimental analysis of the mechanical effects that result when tissue models are irradiated with nanosecond laser pulses to elucidate the relative contribution of linear and nonlinear absorption to bubble formation. Furthermore, we investigate cavitation bubble formation with temperature increments as low as 3 °C.

  12. Photoemission in nanosecond and picosecond regimes obtained from macro and micro cathodes

    International Nuclear Information System (INIS)

    Boussoukaya, M.; Bergeret, H.; Chehab, R.; Leblond, B.; Franco, M.

    1987-03-01

    For Lasertron studies at LAL, results obtained from tests on different photocathodes are given below. Using respectively two Nd: YAG lasers (a nanosecond one and a picosecond one) we have determined the level and the intensity of pulsed photoemission and the photoelectric yield in UV, green and infrared lights. We obtained a total current of more than 1 A with nanosecond width from a single W needle, and photoconversion yield of more than 1 was reached in green and UV lights. In classical pulsed photoemission, obtained photoconversion yield from LaB 6 photocathode was of about 10 -3 in higher fields

  13. A microchannel plate X-ray multiplier with rising-time less than 170 ps

    International Nuclear Information System (INIS)

    Zhao Shicheng; Ouyang Bin

    1987-01-01

    The time reponse of a microchannel plate X-ray multiplier has been improved considerably by using a coupling construction of coaxial tapers. The experimental calibration results with laser plasma X-ray source show that the rising-time of the multiplier is less than 170 ps

  14. Nanosecond repetitively pulsed discharges in air at atmospheric pressure-the spark regime

    International Nuclear Information System (INIS)

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

    2010-01-01

    Nanosecond repetitively pulsed (NRP) spark discharges have been studied in atmospheric pressure air preheated to 1000 K. Measurements of spark initiation and stability, plasma dynamics, gas temperature and current-voltage characteristics of the spark regime are presented. Using 10 ns pulses applied repetitively at 30 kHz, we find that 2-400 pulses are required to initiate the spark, depending on the applied voltage. Furthermore, about 30-50 pulses are required for the spark discharge to reach steady state, following initiation. Based on space- and time-resolved optical emission spectroscopy, the spark discharge in steady state is found to ignite homogeneously in the discharge gap, without evidence of an initial streamer. Using measured emission from the N 2 (C-B) 0-0 band, it is found that the gas temperature rises by several thousand Kelvin in the span of about 30 ns following the application of the high-voltage pulse. Current-voltage measurements show that up to 20-40 A of conduction current is generated, which corresponds to an electron number density of up to 10 15 cm -3 towards the end of the high-voltage pulse. The discharge dynamics, gas temperature and electron number density are consistent with a streamer-less spark that develops homogeneously through avalanche ionization in volume. This occurs because the pre-ionization electron number density of about 10 11 cm -3 produced by the high frequency train of pulses is above the critical density for streamer-less discharge development, which is shown to be about 10 8 cm -3 .

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

    Science.gov (United States)

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

    2010-12-01

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

  16. Nanosecond repetitively pulsed discharges in air at atmospheric pressure-the spark regime

    Energy Technology Data Exchange (ETDEWEB)

    Pai, David Z; Lacoste, Deanna A; Laux, Christophe O [Laboratoire EM2C, CNRS UPR288, Ecole Centrale Paris, 92295 Chatenay-Malabry (France)

    2010-12-15

    Nanosecond repetitively pulsed (NRP) spark discharges have been studied in atmospheric pressure air preheated to 1000 K. Measurements of spark initiation and stability, plasma dynamics, gas temperature and current-voltage characteristics of the spark regime are presented. Using 10 ns pulses applied repetitively at 30 kHz, we find that 2-400 pulses are required to initiate the spark, depending on the applied voltage. Furthermore, about 30-50 pulses are required for the spark discharge to reach steady state, following initiation. Based on space- and time-resolved optical emission spectroscopy, the spark discharge in steady state is found to ignite homogeneously in the discharge gap, without evidence of an initial streamer. Using measured emission from the N{sub 2} (C-B) 0-0 band, it is found that the gas temperature rises by several thousand Kelvin in the span of about 30 ns following the application of the high-voltage pulse. Current-voltage measurements show that up to 20-40 A of conduction current is generated, which corresponds to an electron number density of up to 10{sup 15} cm{sup -3} towards the end of the high-voltage pulse. The discharge dynamics, gas temperature and electron number density are consistent with a streamer-less spark that develops homogeneously through avalanche ionization in volume. This occurs because the pre-ionization electron number density of about 10{sup 11} cm{sup -3} produced by the high frequency train of pulses is above the critical density for streamer-less discharge development, which is shown to be about 10{sup 8} cm{sup -3}.

  17. Sub-nanosecond clock synchronization and trigger management in the nuclear physics experiment AGATA

    International Nuclear Information System (INIS)

    Bellato, M; Isocrate, R; Rampazzo, G; Bazzacco, D; Bortolato, D; Triossi, A; Chavas, J; Mengoni, D; Recchia, F

    2013-01-01

    The new-generation spectrometer AGATA, the Advanced GAmma Tracking Array, requires sub-nanosecond clock synchronization among readout and front-end electronics modules that may lie hundred meters apart. We call GTS (Global Trigger and Synchronization System) the infrastructure responsible for precise clock synchronization and for the trigger management of AGATA. It is made of a central trigger processor and nodes, connected in a tree structure by means of optical fibers operated at 2Gb/s. The GTS tree handles the synchronization and the trigger data flow, whereas the trigger processor analyses and eventually validates the trigger primitives centrally. Sub-nanosecond synchronization is achieved by measuring two different types of round-trip times and by automatically correcting for phase-shift differences. For a tree of depth two, the peak-to-peak clock jitter at each leaf is 70 ps; the mean phase difference is 180 ps, while the standard deviation over such phase difference, namely the phase equalization repeatability, is 20 ps. The GTS system has run flawlessly for the two-year long AGATA campaign, held at the INFN Legnaro National Laboratories, Italy, where five triple clusters of the AGATA sub-array were coupled with a variety of ancillary detectors

  18. Sub-nanosecond clock synchronization and trigger management in the nuclear physics experiment AGATA

    Science.gov (United States)

    Bellato, M.; Bortolato, D.; Chavas, J.; Isocrate, R.; Rampazzo, G.; Triossi, A.; Bazzacco, D.; Mengoni, D.; Recchia, F.

    2013-07-01

    The new-generation spectrometer AGATA, the Advanced GAmma Tracking Array, requires sub-nanosecond clock synchronization among readout and front-end electronics modules that may lie hundred meters apart. We call GTS (Global Trigger and Synchronization System) the infrastructure responsible for precise clock synchronization and for the trigger management of AGATA. It is made of a central trigger processor and nodes, connected in a tree structure by means of optical fibers operated at 2Gb/s. The GTS tree handles the synchronization and the trigger data flow, whereas the trigger processor analyses and eventually validates the trigger primitives centrally. Sub-nanosecond synchronization is achieved by measuring two different types of round-trip times and by automatically correcting for phase-shift differences. For a tree of depth two, the peak-to-peak clock jitter at each leaf is 70 ps; the mean phase difference is 180 ps, while the standard deviation over such phase difference, namely the phase equalization repeatability, is 20 ps. The GTS system has run flawlessly for the two-year long AGATA campaign, held at the INFN Legnaro National Laboratories, Italy, where five triple clusters of the AGATA sub-array were coupled with a variety of ancillary detectors.

  19. Monopole patch antenna for in vivo exposure to nanosecond pulsed electric fields.

    Science.gov (United States)

    Merla, C; Apollonio, F; Paffi, A; Marino, C; Vernier, P T; Liberti, M

    2017-07-01

    To explore the promising therapeutic applications of short nanosecond electric pulses, in vitro and in vivo experiments are highly required. In this paper, an exposure system based on monopole patch antenna is reported to perform in vivo experiments on newborn mice with both monopolar and bipolar nanosecond signals. Analytical design and numerical simulations of the antenna in air were carried out as well as experimental characterizations in term of scattering parameter (S 11 ) and spatial electric field distribution. Numerical dosimetry of the setup with four newborn mice properly placed in proximity of the antenna patch was carried out, exploiting a matching technique to decrease the reflections due to dielectric discontinuities (i.e., from air to mouse tissues). Such technique consists in the use of a matching dielectric box with dielectric permittivity similar to those of the mice. The average computed electric field inside single mice was homogeneous (better than 68 %) with an efficiency higher than 20 V m -1  V -1 for the four exposed mice. These results demonstrate the possibility of a multiple (four) exposure of small animals to short nanosecond pulses (both monopolar and bipolar) in a controlled and efficient way.

  20. Removal of Tattoos by Q-Switched Nanosecond Lasers.

    Science.gov (United States)

    Karsai, Syrus

    2017-01-01

    Tattoo removal by Q-switched nanosecond laser devices is generally a safe and effective method, albeit a time-consuming one. Despite the newest developments in laser treatment, it is still not possible to remove every tattoo completely and without complications. Incomplete removal remains one of the most common challenges. As a consequence, particular restraint should be exercised when treating multicoloured tattoos, and patients need to be thoroughly informed about remaining pigment. Other frequent adverse effects include hyper- and hypopigmentation as well as ink darkening; the latter is particularly frequent in permanent make-up. Scarring is also possible, although it is rare when treatment is performed correctly. It is becoming more widespread for laser operators to encounter allergic reactions and even malignant tumours in tattoos, and treating these conditions requires a nuanced approach. © 2017 S. Karger AG, Basel.

  1. Plasma surface treatment of Cu by nanosecond-pulse diffuse discharges in atmospheric air

    Science.gov (United States)

    Cheng, ZHANG; Jintao, QIU; Fei, KONG; Xingmin, HOU; Zhi, FANG; Yu, YIN; Tao, SHAO

    2018-01-01

    Nanosecond-pulse diffuse discharges could provide high-density plasma and high-energy electrons at atmospheric pressure. In this paper, the surface treatment of Cu by nanosecond-pulse diffuse discharges is conducted in atmospheric air. Factors influencing the water contact angle (WCA), chemical composition and microhardness, such as the gap spacing and treatment time, are investigated. The results show that after the plasma surface treatment, the WCA considerably decreases from 87° to 42.3°, and the surface energy increases from 20.46 mJ m-2 to 66.28 mJ m-2. Results of energy dispersive x-ray analysis show that the concentration of carbon decreases, but the concentrations of oxygen and nitrogen increase significantly. Moreover, the microhardness increases by approximately 30% after the plasma treatment. The aforementioned changes on the Cu surface indicate the plasma surface treatment enhances the hydrophilicity and microhardness, and it cleans the carbon and achieves oxidization on the Cu surface. Furthermore, by increasing the gap spacing and treatment time, better treatment effects can be obtained. The microhardness in the case of a 2.5 cm gap is higher than that in the case of a 3 cm gap. More oxygen and nitrogen species appear on the Cu surface for the 2.5 cm gap treatment than for the 3 cm gap treatment. The WCA significantly decreases with the treatment time when it is no longer than 90 s, and then it reaches saturation. In addition, more oxygen-containing and nitrogen-containing groups appear after extended plasma treatment time. They contribute to the improvement of the hydrophilicity and oxidation on the Cu surface.

  2. Comparison of vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification systems.

    Science.gov (United States)

    Han, Young Keun; Miller, Kevin M

    2009-08-01

    To compare vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification machines. Jules Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. The vacuum rise time under normal and enhanced aspiration modes, vacuum limit accuracy, and occlusion break surge of the Infiniti Vision System, Stellaris Vision Enhancement System, and WhiteStar Signature Phacoemulsification System were tested. Vacuum rise time and limit accuracy were measured at limit settings of 400 mm Hg and 600 mm Hg. Surge area was recorded at vacuum limit settings of 200 mm Hg, 300 mm Hg, 400 mm Hg, and 500 mm Hg. The Infiniti had the fastest vacuum rise times under normal and enhanced aspiration modes. At 4 seconds, the vacuum limit accuracy was greatest with the Infiniti at the 400 mm Hg limit and the Signature at the 600 mm Hg limit. The Stellaris did not reach either vacuum target. The Infiniti performed better than the other 2 machines during testing of occlusion break surge at all vacuum limit settings above 200 mm Hg. Under controlled laboratory test conditions, the Infiniti had the fastest vacuum rise time, greatest vacuum limit accuracy at 400 mm Hg, and least occlusion break surge. These results can be explained by the lower compliance of the Infiniti system.

  3. Fiber Coupled Pulse Shaper for Sub-Nanosecond Pulse Lidar, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase II effort will develop an all-diode laser and fiber optic based, single frequency, sub-nanosecond pulsed laser source...

  4. Thermodynamics of nanosecond nanobubble formation at laser-excited metal nanoparticles

    International Nuclear Information System (INIS)

    Siems, A; Weber, S A L; Boneberg, J; Plech, A

    2011-01-01

    The nonlinear thermal behavior of laser-heated gold nanoparticles in aqueous suspension is determined by time-resolved optical spectroscopy and x-ray scattering. The nanoparticles can be excited transiently to high lattice temperatures owing to their large absorption cross-section and slow heat dissipation to the surrounding. A consequence is the observation of lattice expansion, changed optical transmission, vapor bubble formation or particle melting. The heat transfer equations are solved for two limiting cases of heat pulses shorter and longer than the characteristic cooling time. The results of pulsed excitation with femtosecond and nanosecond lasers are explained by the theoretical prediction, and the bubble formation is interpreted by a spinodal decomposition at the particle-liquid interface. It is shown that both the laser spectroscopy and x-ray scattering results agree qualitatively and quantitatively, underlining the validity of the comprehensive model.

  5. Low-dielectric layer increases nanosecond electric discharges in distilled water

    KAUST Repository

    Hamdan, Ahmad; Cha, Min

    2016-01-01

    decreasing of the energy consumption are the main goals of today’s research. Here we present an experimental study of nanosecond discharge in distilled water covered by a layer of dielectric material. We demonstrate through this paper that the discharge

  6. Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

    Energy Technology Data Exchange (ETDEWEB)

    Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.; Aziz, Michael J.; Mazur, Eric [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Rekemeyer, Paul H.; Gradečak, Silvija [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-12-14

    Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintaining high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.

  7. Towards a laser fluence dependent nanostructuring of thin Au films on Si by nanosecond laser irradiation

    International Nuclear Information System (INIS)

    Ruffino, F.; Pugliara, A.; Carria, E.; Romano, L.; Bongiorno, C.; Fisicaro, G.; La Magna, A.; Spinella, C.; Grimaldi, M.G.

    2012-01-01

    Highlights: ► Au nanoclusters are produced by nanosecond laser irradiations of thin Au film on Si. ► The shape, size, and surface density of the Au nanoclusters are tunable by laser fluence. ► The formation dynamic of the Au nanoclusters under nanosecond laser irradiation is analyzed. - Abstract: In this work, we study the nanostructuring effects of nanosecond laser irradiations on 5 nm thick Au film sputter-deposited on Si. After deposition of Au on Si substrate, nanosecond laser irradiations were performed increasing the laser fluence from 750 to 1500 mJ/cm 2 . Several analyses techniques, such as Rutherford backscattering spectrometry, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy were crossed to study the morphological evolution of the Au film as a function of laser fluence. In particular, the formation of Au nanoparticles was observed. The analyses allowed a quantitative evaluation of the evolution of the nanoparticles size, surface density, and shape as a function of the laser fluence. Therefore, a control the structural properties of the Au nanoparticles is reached, for example, for applications in Si nanowires growth or plasmonics.

  8. Study of the pulsation of an ion accelerator giving 20 nano-second pulses; Etude de la pulsation d'un accelerateur d'ions fournissant des impulsions d'une duree de 20 nano-secondes

    Energy Technology Data Exchange (ETDEWEB)

    Cosnac, B de [Commissariat a l' Energie Atomique, Fontenay aux Roses (France). Centre d' Etudes Nucleaires

    1965-03-01

    In order to measure fast neutron spectra by the time-of-flight method, we have studied a pulsed ion-source which has been placed on the 600 kV electrostatic accelerator at Fontenay-aux-Roses. We examine successively: the ion-source itself, its extraction device, the focussing equipment and the pulsation system constituted by a slit which is swept by the beam. Using this ion-source it is possible to obtain a direct current of deutons of over 800 {mu}A, and clouds having a duration which can be adjusted to between 15 and 40 nano-seconds. (author) [French] Pour mesurer des spectres de neutrons rapides par la methode de temps de vol, nous avons etudie une source d'ions pulsee qui a ete placee sur l'accelerateur electrostatique de 600 kV de Fontenay-aux-Roses. Nous examinons successivement: la source d'ions elle-meme, son dispositif d'extraction, l'optique de focalisation et le systeme de pulsation constituee par le balayage du faisceau devant une fente. La source d'ions permet d'obtenir un courant continu de deutons superieur a 800 {mu}A et des bouffees d'une duree reglable comprise entre 15 et 40 nanosecondes. (auteur)

  9. Mechanical response of agar gel irradiated with Nd:YAG nanosecond laser pulses

    Science.gov (United States)

    Pérez-Gutiérrez, Francisco G.; Evans, Rodger; Camacho-López, Santiago; Aguilar, Guillermo

    2010-02-01

    Nanosecond long laser pulses are used in medical applications where precise tissue ablation with minimal thermal and mechanical collateral damage is required. When a laser pulse is incident on a material, optical energy will be absorbed by a combination of linear and nonlinear absorption according to both: laser light intensity and material properties. In the case of water or gels, the first results in heat generation and thermoelastic expansion; while the second results in an expanding plasma formation that launches a shock wave and a cavitation/boiling bubble. Plasma formation due to nonlinear absorption of nanosecond laser pulses is originated by a combination of multiphoton ionization and thermionic emission of free electrons, which is enhanced when the material has high linear absorption coefficient. In this work, we present measurements of pressure transients originated when 6 ns laser pulses are incident on agar gels with varying linear absorption coefficient, mechanical properties and irradiation geometry using laser radiant exposures above threshold for bubble formation. The underlying hypothesis is that pressure transients are composed of the superposition of both: shock wave originated by hot expanding plasma resulting from nonlinear absorption of optical energy and, thermoelastic expansion originated by heat generation due to linear absorption of optical energy. The objective of this work is to evaluate the relative contribution of each absorption mechanism to mechanical effects in agar gel. Real time pressure transients are recorded with PVDF piezoelectric sensors and time-resilved imaging from 50 μm to 10 mm away from focal point.

  10. Study of spatiotemporal dynamics of a nanosecond atmospheric-pressure dielectric barrier discharge in millimeter-long air gaps

    Energy Technology Data Exchange (ETDEWEB)

    Malashin, M. V.; Moshkunkov, S. I.; Khomich, V. Yu.; Shershunova, E. A., E-mail: eshershunova@gmail.com [Russian Academy of Sciences, Institute for Electrophysics and Electric Power (Russian Federation)

    2017-02-15

    The spatiotemporal dynamics of a nanosecond atmospheric-pressure dielectric barrier discharge in 1- to 3-mm-long air gaps was studied experimentally. By using a segmented electrode, data on the time evolution of the discharge in different regions of the discharge gap were obtained. The uniformity of the discharge over the cross section is estimated by analyzing the spatial distribution of its glow.

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

    International Nuclear Information System (INIS)

    TROYER, G.L.

    2000-01-01

    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

  12. High-voltage nanosecond pulse shaper

    International Nuclear Information System (INIS)

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

    1987-01-01

    A high-voltage pulse shaper with an output of up to 250 kV, a base duration of ∼ 10 nsec, and a repetition frequency of 50 pulses/sec is described. The described high-voltage nanosecond pulse shaper is designed for one-orbit extraction of an electron beam from a betatron. A diagram of the pulse shaper, which employs a single-stage generator is shown. The shaping element is a low-inductance capacitor bank of series-parallel KVI-3 (2200 pF at 10 kV) or K15-10 (4700 pF at 31.5 kV) disk ceramic capacitors. Four capacitors are connected in parallel and up to 25 are connected in series

  13. Nanosecond radar system based on repetitive pulsed relativistic BWO

    International Nuclear Information System (INIS)

    Bunkin, B.V.; Gaponov-Grekhov, A.V.; Eltchaninov, A.S.; Zagulov, F.Ya.; Korovin, S.D.; Mesyats, G.A.; Osipov, M.L.; Otlivantchik, E.A.; Petelin, M.I.; Prokhorov, A.M.

    1993-01-01

    The paper presents the results of studies of a nanosecond radar system based on repetitive pulsed relativistic BWO. A pulsed power repetitive accelerator producing electron beams of electron energy 500-700 keV and current 5 kA in pulses of duraction 10 ns with a repetition rate of 100 pps is described. The results of experiments with a high-voltage gas-filled spark gap and a cold-cathode vacuum diode under the conditions of high repetition rates are given. Also presented are the results of studies of a relativistic BWO operating with a wavelength of 3 cm. It is shown that for a high-current beam electron energy of 500-700 keV, the BWO efficiency can reach 35%, the microwave power being 10 9 W. A superconducting solenoid creating a magnetic field of 30 kOe was used for the formation and transportation of the high-current electron beam. In conclusion, the outcome of tests of a nanosecond radar station based on a pulsed power repetitive accelerator and a relativistic BWO is reported

  14. Effects of drive current rise-time and initial load density distribution on Z-pinch characteristics

    Institute of Scientific and Technical Information of China (English)

    Duan Yao-Yong; Guo Yong-Hui; Wang Wen-Sheng; Qiu Ai-Ci

    2005-01-01

    A two-dimensional, three-temperature radiation magneto-hydrodynamics model is applied to the investigation of evolutional trends in x-ray radiation power, energy, peak plasma temperature and density as functions of drive current rise-time and initial load density distribution by using the typical experimental parameters of tungsten wire-array Z-pinch on the Qiangguang-Ⅰ generator. The numerical results show that as the drive current rise-time is shortened, x-ray radiation peak power, energy, peak plasma density and peak ion temperature increase approximately linearly, but among them the x-ray radiation peak power increases more quickly. As the initial plasma density distribution in the radial direction becomes gradually flattened, the peak radiation power and the peak ion-temperature almost exponentially increase, while the radiation energy and the peak plasma density change only a little. The main effect of shortening drive current rise-time is to enhance compression of plasma, and the effect of flattening initial load density distribution in the radial direction is to raise the plasma temperature. Both of the approaches elevate the x-ray peak radiation power.

  15. Effect of rise-time patterns on dynamics of sheath expansion during plasma immersion ion implantation

    International Nuclear Information System (INIS)

    Huang Yongxian; Tian Xiubo; Yang Shiqin; Fu Ricky; Paul, C.K.

    2007-01-01

    Plasma immersion ion implantation (PIII) has been developed as a low-cost and efficient surface modification technique of irregularly-shaped objects. The effect of six pulse waves with different rise-time patterns on the spatio-temporal evolution of plasma sheath,energy and dose of ion implantation has been simulated by particle-in-cell modeling. Statistical results may be obtained through assuming the Boltzmann distribution of electrons, and solving Poisson and Newton equations for tracing each ion in the plasma sheath. The results show that rise-time pattern has a critical influence on the evolution of plasma sheath. There exists maximum thickness difference of plasma sheath for different waveforms. The acceleration of ions is non-uniform due to the non-uniformity of electrical field strength. The maximum gradient of electrical field appears near the edge of plasma sheath. The results also show that optimization of dose and energy of incident ions may be achieved through modification of rise-time pattern. The numerical simulation of sheath expansion can be effectively used to provide a scientific basis for optimizing the PIII process. (authors)

  16. Quad precision delay generator

    International Nuclear Information System (INIS)

    Krishnan, Shanti; Gopalakrishnan, K.R.; Marballi, K.R.

    1997-01-01

    A Quad Precision Delay Generator delays a digital edge by a programmed amount of time, varying from nanoseconds to microseconds. The output of this generator has an amplitude of the order of tens of volts and rise time of the order of nanoseconds. This was specifically designed and developed to meet the stringent requirements of the plasma focus experiments. Plasma focus is a laboratory device for producing and studying nuclear fusion reactions in hot deuterium plasma. 3 figs

  17. Nanosecond time measurements of single pulse

    International Nuclear Information System (INIS)

    Xing Jingyuan; Cheng Shiyuan

    1986-01-01

    This report mainly describes the principle specification of circuit design and time-interval calibrations of model SHS 500 time-to-digital converter. Its range is 12 to 500 ns, with six ranges: 50, 100, 200, 300, 400 and 500 ns. The precision of measured time-interval is 0.3% of full scale and time resolution is 0.1% of full scale

  18. Comparison of two picosecond lasers to a nanosecond laser for treating tattoos: a prospective randomized study on 49 patients.

    Science.gov (United States)

    Lorgeou, A; Perrillat, Y; Gral, N; Lagrange, S; Lacour, J-P; Passeron, T

    2018-02-01

    Q-switched nanosecond lasers demonstrated their efficacy in treating most types of tattoos, but complete disappearance is not always achieved even after performing numerous laser sessions. Picosecond lasers are supposed to be more efficient in clearing tattoos than nanosecond lasers, but prospective comparative data remain limited. To compare on different types of tattoos the efficacy of a nanosecond laser with two types of picosecond lasers. We conducted a prospective randomized study performed from December 2014 to June 2016 on adult patients with all types of tattoos. The tattoos were divided into two halves of equal size. After randomization, half of the tattoo was treated with a picosecond laser and the other half with a nanosecond laser. The evaluation was performed on standardized pictures performed before treatment and 2 months after the last session, by two physicians, not involved in the treatment, blinded on the type of treatments received. The main end point was a clearance above 75% of the tattoos. A total of 49 patients were included. Professional tattoos represented 85.7%, permanent make-up 8.2% and non-professional tattoo 6.1%. The majority were black or blue and 10.2% were polychromatic. No patient was lost during follow-up. A reduction of 75% or more of the colour intensity was obtained for 33% of the tattoos treated with the picosecond lasers compared to 14% with the nanosecond laser (P = 0.008). An improvement superior to 75% was obtained in 34% monochromic black or blue tattoos with the picosecond lasers compared to 9% for the nanosecond laser. Only one of the five polychromic tattoos achieved more than 75% of improvement with the two types of laser. Our results show a statistically significant superiority of the picosecond lasers compared to the nanosecond laser for tattoo clearance. However, they do not show better efficacy for polychromic tattoos and the difference in terms of side-effects was also minimal with a tendency of picosecond

  19. Nanosecond dynamics of influenza A/M2TM and an amantadine resistant mutant probed by time-dependent red shifts of a native tryptophan

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Vikas [Center for Advanced Biotechnology and Medicine, Robert Wood Johnson Medical School – UMDNJ, Piscataway, NJ 08854 (United States); Department of Biochemistry, Robert Wood Johnson Medical School – UMDNJ, Piscataway, NJ 08854 (United States); Cristian, Lidia [Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6059 (United States); Toptygin, Dmitri; Brand, Ludwig [Department of Biology, Johns Hopkins University, Baltimore, MD 21218 (United States); DeGrado, William F., E-mail: William.Degrado@ucsf.edu [Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158 (United States)

    2013-08-30

    Highlights: ► Examined nanosecond dynamics of essential tryptophan residue of M2 proton channel. ► Channel blocking drugs restrict the ability of M2 to stabilize charge. ► Dielectric relaxation of M2 consistent with molecular dynamics simulation studies. - Abstract: Proteins involved in functions such as electron transfer or ion transport must be capable of stabilizing transient charged species on time scales ranging from picoseconds to microseconds. We study the influenza A M2 proton channel, containing a tryptophan residue that serves as an essential part of the proton conduction pathway. We induce a transition dipole in tryptophan by photoexcitation, and then probe the dielectric stabilization of its excited state. The magnitude of the stabilization over this time regime was larger than that generally found for tryptophan in membrane or protein environments. M2 achieves a water-like stabilization over a 25 ns time scale, slower than that of bulk water, but sufficiently rapid to contribute to stabilization of charge as protons diffuse through the channel. These measurements should stimulate future MD studies to clarify the role of sidechain versus non-bulk water in defining the process of relaxation.

  20. Factors Influencing Time Resolution of Scintillators and Ways to Improve Them

    CERN Document Server

    Lecoq, P; Brunner, S; Meyer, T; Auffray, E; Knapitsch, A; Jarron, P

    2010-01-01

    The renewal of interest in Time of Flight Positron Emission Tomography (TOF-PET), as well as the necessity to precisely tag events in high energy physics (HEP) experiments at future colliders are pushing for an optimization of all factors affecting the time resolution of the whole acquisition chain comprising the crystal, the photo detector, and the electronics. The time resolution of a scintillator-based detection system is determined by the rate of photo electrons at the detection threshold, which depends on the time distribution of photons being converted in the photo detector. The possibility to achieve time resolution of about 100 ps Full Width at Half Maximum (FWHM) requires an optimization of the light production in the scintillator, the light transport and its transfer from the scintillator to the photo detector. In order to maximize the light yield, and in particular the density of photons in the first nanosecond, while minimizing the rise time and decay time, particular attention must be paid to the...

  1. Nanosecond-timescale spin transfer using individual electrons in a quadruple-quantum-dot device

    Energy Technology Data Exchange (ETDEWEB)

    Baart, T. A.; Jovanovic, N.; Vandersypen, L. M. K. [QuTech and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft (Netherlands); Reichl, C.; Wegscheider, W. [Solid State Physics Laboratory, ETH Zürich, 8093 Zürich (Switzerland)

    2016-07-25

    The ability to coherently transport electron-spin states between different sites of gate-defined semiconductor quantum dots is an essential ingredient for a quantum-dot-based quantum computer. Previous shuttles using electrostatic gating were too slow to move an electron within the spin dephasing time across an array. Here, we report a nanosecond-timescale spin transfer of individual electrons across a quadruple-quantum-dot device. Utilizing enhanced relaxation rates at a so-called hot spot, we can upper bound the shuttle time to at most 150 ns. While actual shuttle times are likely shorter, 150 ns is already fast enough to preserve spin coherence in, e.g., silicon based quantum dots. This work therefore realizes an important prerequisite for coherent spin transfer in quantum dot arrays.

  2. Correction of incomplete charge collection in CdTe detectors using the correlation with the rise time distribution

    International Nuclear Information System (INIS)

    Horovitz, Yossi.

    1994-01-01

    Experimentally and theoretically it was found that there is a correlation between tile pulse rise time and the amount of charge that is collected in the detector contacts. As the rise time becomes longer less charge is collected. In this thesis it has been proven that one can find from this correlation, with the aid of a mathematical function, the theoretical amount of charge that has to be collected in the contacts if no trapping took place. This mathematical function called the correction function, f(t), is dependent on the rise time and the material quality (the trap concentration). In order to find the correction function, a computer, simulation was written. This computer program simulates, based on a phenomenological theoretical model, the charge collection in the detector. This model depends on three parameters (for the holes and for the electrons) that characterized the charge collection quality of the detector. The parameters are: the mean free time to be trapped, the detrapping time and the transit time that depends on the electric field. By a comparison between the simulation output and experimental data, these parameters were found. The correction function was found to be linear with rise time. This conclusion is confirmed experimentally. In this work experiments have been carried out that measured the correlation between two parameters. These experiments measured, for each photon that interacts with the detector, the pulse rise time and the pulse amplitude. A computer program accepts these spectra and substitute each element in the correction function and corrects for the incomplete charge collection. It was found that the correction function does not depend on the energy of the radiation source and source-detector geometry but depends on the material quality. The application of the correction function to the two dimensional spectra gives a correction of tens of percents in charge collection and provides an improvement in the resolution and the peak

  3. Electric field measurements in nanosecond pulse discharges in air over liquid water surface

    Science.gov (United States)

    Simeni Simeni, Marien; Baratte, Edmond; Zhang, Cheng; Frederickson, Kraig; Adamovich, Igor V.

    2018-01-01

    Electric field in nanosecond pulse discharges in ambient air is measured by picosecond four-wave mixing, with absolute calibration by a known electrostatic field. The measurements are done in two geometries, (a) the discharge between two parallel cylinder electrodes placed inside quartz tubes, and (b) the discharge between a razor edge electrode and distilled water surface. In the first case, breakdown field exceeds DC breakdown threshold by approximately a factor of four, 140 ± 10 kV cm-1. In the second case, electric field is measured for both positive and negative pulse polarities, with pulse durations of ˜10 ns and ˜100 ns, respectively. In the short duration, positive polarity pulse, breakdown occurs at 85 kV cm-1, after which the electric field decreases over several ns due to charge separation in the plasma, with no field reversal detected when the applied voltage is reduced. In a long duration, negative polarity pulse, breakdown occurs at a lower electric field, 30 kV cm-1, after which the field decays over several tens of ns and reverses direction when the applied voltage is reduced at the end of the pulse. For both pulse polarities, electric field after the pulse decays on a microsecond time scale, due to residual surface charge neutralization by transport of opposite polarity charges from the plasma. Measurements 1 mm away from the discharge center plane, ˜100 μm from the water surface, show that during the voltage rise, horizontal field component (Ex ) lags in time behind the vertical component (Ey ). After breakdown, Ey is reduced to near zero and reverses direction. Further away from the water surface (≈0.9 mm), Ex is much higher compared to Ey during the entire voltage pulse. The results provide insight into air plasma kinetics and charge transport processes near plasma-liquid interface, over a wide range of time scales.

  4. Measuring Sea Level Rise-Induced Shoreline Changes and Inundation in Real Time

    Science.gov (United States)

    Shilling, F.; Waetjen, D.; Grijalva, E.

    2016-12-01

    We describe a method to monitor shoreline inundation and changes in response to sea level rise (SLR) using a network of time-lapse cameras. We found for coastal tidal marshes that this method was sensitive to vertical changes in sea level of 20 cm has occurred in the San Francisco Bay and other US coastal areas and is likely to rise by another 30-45 cm by mid-century, which will flood and erode many coastal ecosystems, highways, and urban areas. This rapid degree of rise means that it is imperative to co-plan for natural and built systems. Many public facilities are adjacent to shoreline ecosystems, which both protect infrastructure from wave and tide energy and are home to regulated species and habitats. Accurate and timely information about the actual extent of SLR impacts to shorelines will be critical during built-system adaptation. Currently, satellite-sourced imagery cannot provide the spatial or temporal resolution necessary to investigate fine-scale shoreline changes, leaving a gap between predictive models and knowing how, where and when these changes are occurring. The method described is feasible for near-term (1 to 10 years) to long-term application and can be used for measuring fine-resolution shoreline changes (organize photographs that could be combined with related external data (e.g., gauged water levels) to create an information mashup. This information could be used to validate models predicting shoreline inundation and loss, inform SLR-adaptation planning, and to visualize SLR impacts to the public.

  5. Electroporation of Mammalian Cells by Nanosecond Electric Field Oscillations and its Inhibition by the Electric Field Reversal

    Science.gov (United States)

    2015-09-08

    Report 3. DATES COVERED (From – To) March 2013 to July 2015 4. TITLE AND SUBTITLE Electroporation of mammalian cells by nanosecond electric field...Prescribed by ANSI Std. Z39.18 1Scientific RepoRts | 5:13818 | DOi: 10.1038/srep13818 www.nature.com/scientificreports Electroporation of mammalian cells...first to demonstrate that mammalian cells can be electroporated by damped sine wave electric stimuli of nanosecond duration. By comparing the

  6. Supershort avalanche electron beams and x-ray in high-pressure nanosecond discharges

    International Nuclear Information System (INIS)

    Tarasenko, V F; Baksht, E H; Kostyrya, I D; Lomaev, M I; Rybka, D V

    2008-01-01

    The properties of a supershort avalanche electron beam (S AEB) and X-ray radiation produced using a nanosecond volume discharge are examined. An electron beam of the runaway electrons with amplitude of ∼ 50 A has been obtained in air atmospheric pressure. It is reported that S AEB is formed in the angle above 2π sr. Three groups of the runaway electrons are formed in a gas diode under atmospheric air pressure, when nanosecond voltage pulses with amplitude of hundreds of kilovolts are applied. The electron beam has been generated behind a 45 μm thick AlBe foil in SF 6 and Xe under the pressure of 2 arm, and in He under the pressure of about 12 atm. The paper gives the analysis of a generation mechanism of SAEB.

  7. Nanosecond laser therapy reverses pathologic and molecular changes in age-related macular degeneration without retinal damage.

    Science.gov (United States)

    Jobling, A I; Guymer, R H; Vessey, K A; Greferath, U; Mills, S A; Brassington, K H; Luu, C D; Aung, K Z; Trogrlic, L; Plunkett, M; Fletcher, E L

    2015-02-01

    Age-related macular degeneration (AMD) is a leading cause of vision loss, characterized by drusen deposits and thickened Bruch's membrane (BM). This study details the capacity of nanosecond laser treatment to reduce drusen and thin BM while maintaining retinal structure. Fifty patients with AMD had a single nanosecond laser treatment session and after 2 yr, change in drusen area was compared with an untreated cohort of patients. The retinal effect of the laser was determined in human and mouse eyes using immunohistochemistry and compared with untreated eyes. In a mouse with thickened BM (ApoEnull), the effect of laser treatment was quantified using electron microscopy and quantitative PCR. In patients with AMD, nanosecond laser treatment reduced drusen load at 2 yr. Retinal structure was not compromised in human and mouse retina after laser treatment, with only a discrete retinal pigment epithelium (RPE) injury, and limited mononuclear cell response observed. BM was thinned in the ApoEnull mouse 3 mo after treatment (ApoEnull treated 683 ± 38 nm, ApoEnull untreated 890 ± 60 nm, C57Bl6J 606 ± 43 nm), with the expression of matrix metalloproteinase-2 and -3 increased (>260%). Nanosecond laser resolved drusen independent of retinal damage and improved BM structure, suggesting this treatment has the potential to reduce AMD progression. © FASEB.

  8. Current-Voltage Characteristic of Nanosecond - Duration Relativistic Electron Beam

    Science.gov (United States)

    Andreev, Andrey

    2005-10-01

    The pulsed electron-beam accelerator SINUS-6 was used to measure current-voltage characteristic of nanosecond-duration thin annular relativistic electron beam accelerated in vacuum along axis of a smooth uniform metal tube immersed into strong axial magnetic field. Results of these measurements as well as results of computer simulations performed using 3D MAGIC code show that the electron-beam current dependence on the accelerating voltage at the front of the nanosecond-duration pulse is different from the analogical dependence at the flat part of the pulse. In the steady-state (flat) part of the pulse), the measured electron-beam current is close to Fedosov current [1], which is governed by the conservation law of an electron moment flow for any constant voltage. In the non steady-state part (front) of the pulse, the electron-beam current is higher that the appropriate, for a giving voltage, steady-state (Fedosov) current. [1] A. I. Fedosov, E. A. Litvinov, S. Ya. Belomytsev, and S. P. Bugaev, ``Characteristics of electron beam formed in diodes with magnetic insulation,'' Soviet Physics Journal (A translation of Izvestiya VUZ. Fizika), vol. 20, no. 10, October 1977 (April 20, 1978), pp.1367-1368.

  9. Hydrophobic treatment on polymethylmethacrylate surface by nanosecond-pulse DBDs in CF4 at atmospheric pressure

    International Nuclear Information System (INIS)

    Zhang, Cheng; Zhou, Yang; Shao, Tao; Xie, Qing; Xu, Jiayu; Yang, Wenjin

    2014-01-01

    Highlights: • Increase in hydrophobicity on PMMA is achieved after the DBD treatment in CF 4 , and the water contact angle can increase from 68° to 100° after treatment. • Nanosecond-pulse DBD is used for the surface treatment and the power density is about 114.8 mW/cm 2 . • The effects of applied voltage, CF 4 flow, and time on plasma treatment are investigated. • Plasma treatment causes morphological change, significantly increases the roughness of the surface, and introduces fluorine-containing groups into the polymethylmethacrylate surface. • Hydrophobic behavior of the treated PMMA surface is slightly affected by the aging effect. - Abstract: Nanosecond-pulse dielectric barrier discharge (DBD) can provide non-thermal plasmas with extremely high energy and high density, which can result in a series of complicated physical and chemical reactions in the surface treatment of polymers. Therefore, in this paper, hydrophobic treatment of polymethylmethacrylate (PMMA) surface is conducted by nanosecond-pulse DBD in carbon tetrafluoride (CF 4 ) at atmospheric pressure. Investigations on surface morphology and chemical composition before and after the DBD treatment in CF 4 are conducted with the contact angle measurement, atomic force microscope, Fourier transform infrared spectroscopy, and X-ray photoelectron spectrometer. The effects of the applied voltage, CF 4 flow rate, and treatment time on the hydrophobic modification are studied. Results show that the contact angles of the treated PMMA surface increases with the applied voltage, and it could be greatly affected by the CF 4 flow rate and the treatment time. The water contact angle can increase from 68° to 100° after the treatment. Furthermore, both surface morphology and chemical composition of the PMMA samples are changed. Both the increase of the surface roughness and the occurrence of fluorine-containing functional groups on the PMMA surface treated by DBD in CF 4 lead to the hydrophobicity

  10. High-voltage nanosecond Marx generator with quasi-rectangular pulses

    International Nuclear Information System (INIS)

    Bulan, V.V.; Grabovskij, E.V.; Gribov, A.N.; Luzhnov, V.G.

    1999-01-01

    The automated high-voltage nanosecond generator, forming single pulses of any polarity on the load of 17 Ohm with polarity voltage from 100 up to 300 kV at the semiheight of 80 ns and the front of 7 ns is described. The generator is assembled on the basis of low-inductive capacitors, which by discharge form the pulse, close by form to rectangular one [ru

  11. Spatial and temporal evolutions of ozone in a nanosecond pulse corona discharge at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Duten, X; Redolfi, M; Aggadi, N; Vega, A; Hassouni, K, E-mail: duten@lspm.cnrs.fr [LSPM-CNRS UPR 3407, Universite Paris Nord, 90 Avenue J.B. Clement, 93430 Villetaneuse (France)

    2011-10-19

    This paper deals with the experimental determination of the spatial and temporal evolutions of the ozone concentration in an atmospheric pressure pulsed plasma, working in the nanosecond regime. We observed that ozone was produced in the localized region of the streamer. The ozone transport requires a characteristic time well above the millisecond. The numerical modelling of the streamer expansion confirms that the hydrodynamic expansion of the filamentary discharge region during the streamer propagation does not lead to a significant transport of atomic oxygen and ozone. It appears therefore that only diffusional transport can take place, which requires a characteristic time of the order of 50 ms.

  12. Spatial and temporal evolutions of ozone in a nanosecond pulse corona discharge at atmospheric pressure

    Science.gov (United States)

    Duten, X.; Redolfi, M.; Aggadi, N.; Vega, A.; Hassouni, K.

    2011-10-01

    This paper deals with the experimental determination of the spatial and temporal evolutions of the ozone concentration in an atmospheric pressure pulsed plasma, working in the nanosecond regime. We observed that ozone was produced in the localized region of the streamer. The ozone transport requires a characteristic time well above the millisecond. The numerical modelling of the streamer expansion confirms that the hydrodynamic expansion of the filamentary discharge region during the streamer propagation does not lead to a significant transport of atomic oxygen and ozone. It appears therefore that only diffusional transport can take place, which requires a characteristic time of the order of 50 ms.

  13. Spatial and temporal evolutions of ozone in a nanosecond pulse corona discharge at atmospheric pressure

    International Nuclear Information System (INIS)

    Duten, X; Redolfi, M; Aggadi, N; Vega, A; Hassouni, K

    2011-01-01

    This paper deals with the experimental determination of the spatial and temporal evolutions of the ozone concentration in an atmospheric pressure pulsed plasma, working in the nanosecond regime. We observed that ozone was produced in the localized region of the streamer. The ozone transport requires a characteristic time well above the millisecond. The numerical modelling of the streamer expansion confirms that the hydrodynamic expansion of the filamentary discharge region during the streamer propagation does not lead to a significant transport of atomic oxygen and ozone. It appears therefore that only diffusional transport can take place, which requires a characteristic time of the order of 50 ms.

  14. Nanosecond laser pulse stimulation of spiral ganglion neurons and model cells.

    Science.gov (United States)

    Rettenmaier, Alexander; Lenarz, Thomas; Reuter, Günter

    2014-04-01

    Optical stimulation of the inner ear has recently attracted attention, suggesting a higher frequency resolution compared to electrical cochlear implants due to its high spatial stimulation selectivity. Although the feasibility of the effect is shown in multiple in vivo experiments, the stimulation mechanism remains open to discussion. Here we investigate in single-cell measurements the reaction of spiral ganglion neurons and model cells to irradiation with a nanosecond-pulsed laser beam over a broad wavelength range from 420 nm up to 1950 nm using the patch clamp technique. Cell reactions were wavelength- and pulse-energy-dependent but too small to elicit action potentials in the investigated spiral ganglion neurons. As the applied radiant exposure was much higher than the reported threshold for in vivo experiments in the same laser regime, we conclude that in a stimulation paradigm with nanosecond-pulses, direct neuronal stimulation is not the main cause of optical cochlea stimulation.

  15. Analysis and Compensation of Dead-Time Effect of a ZVT PWM Inverter Considering the Rise- and Fall-Times

    Directory of Open Access Journals (Sweden)

    Hailin Zhang

    2016-11-01

    Full Text Available The dead-time effect, as an intrinsic problem of the converters based on the half-bridge unit, leads to distortions in the converter output. Although several dead-time effect compensation or elimination methods have been proposed, they cannot fully remove the dead-time effect of blanking delay error, because the output current polarity is difficult detect accurately. This paper utilizes the zero-voltage-switching (ZVT technique to eliminate the blanking delay error, which is the main drawback of the hard-switching inverter, although the technique initially aims to improve the efficiency. A typical ZVT inverter—the auxiliary resonant snubber inverter (ARSI is analyzed. The blanking delay error is completely eliminated in the ARSI. Another error source caused by the finite rise- and fall-times of the voltage is analyzed, which was not considered in the hard-switching inverter. A compensation method based on the voltage error estimation is proposed to compensate the rise- and fall-error. A prototype was developed to verify the effectiveness of the proposed control. Both the simulation and experimental results demonstrate that the qualities of the output current and voltage in the ARSI are better than that in the hard-switching inverter due to the elimination of the blanking delay error. The total harmonic distortion (THD of the output is further reduced by using the proposed compensation method in the ARSI.

  16. Research on the impacts of air temperature on the evolution of nanosecond pulse discharge products

    International Nuclear Information System (INIS)

    Yu, Jin-lu; He, Li-ming; Ding, Wei; Zhao, Zi-chen; Zhang, Hua-lei

    2016-01-01

    Highlights: • Most of the O_2 particles become O_2(V1) in high temperature. • The O_3 molecules are produced mainly by decayed O atoms. • NO molecules are obtained by decayed N_2(A3), N(2D) and N(2P) at the first stage, NO molecules are obtained by decayed N atoms at last. - Abstract: Based on nonequilibrium plasma dynamics of air discharge, the kinetic model simulating plasma discharge products induced by nanosecond pulse discharge in air is presented in this work. Then the paper compares the calculation of model with experimental results of references, and verifies the accuracy of the model. The evolution characteristics of nanosecond pulse discharge plasma under different air temperatures are obtained. Because the O, O_3 and NO have close relationship with the combustion, their formation mechanisms are discussed especially. With increasing temperature, there is no significant addition in O atoms and O_3 molecules. It is found that most of the O_2 molecules become O_2(V1) in higher temperature. The decreasing time of the O atoms is in accordance with the increasing time of O_3 molecules. Thus, the O_3 molecules are produced mainly by decayed O atoms. Increased air temperature will not produce more active particles which could assist the combustion. With the increasing temperature, the particle number density of NO increases fast. At last, they have reached an equilibrium value of the same.

  17. Pure rotational CARS thermometry studies of low-temperature oxidation kinetics in air and ethene-air nanosecond pulse discharge plasmas

    International Nuclear Information System (INIS)

    Zuzeek, Yvette; Choi, Inchul; Uddi, Mruthunjaya; Adamovich, Igor V; Lempert, Walter R

    2010-01-01

    Pure rotational CARS thermometry is used to study low-temperature plasma assisted fuel oxidation kinetics in a repetitive nanosecond pulse discharge in ethene-air at stoichiometric and fuel lean conditions at 40 Torr pressure. Air and fuel-air mixtures are excited by a burst of high-voltage nanosecond pulses (peak voltage, 20 kV; pulse duration, ∼ 25 ns) at a 40 kHz pulse repetition rate and a burst repetition rate of 10 Hz. The number of pulses in the burst is varied from a few pulses to a few hundred pulses. The results are compared with the previously developed hydrocarbon-air plasma chemistry model, modified to incorporate non-empirical scaling of the nanosecond discharge pulse energy coupled to the plasma with number density, as well as one-dimensional conduction heat transfer. Experimental time-resolved temperature, determined as a function of the number of pulses in the burst, is found to agree well with the model predictions. The results demonstrate that the heating rate in fuel-air plasmas is much faster compared with air plasmas, primarily due to energy release in exothermic reactions of fuel with O atoms generated by the plasma. It is found that the initial heating rate in fuel-air plasmas is controlled by the rate of radical (primarily O atoms) generation and is nearly independent of the equivalence ratio. At long burst durations, the heating rate in lean fuel air-mixtures is significantly reduced when all fuel is oxidized.

  18. Plasma-assisted ignition and combustion: nanosecond discharges and development of kinetic mechanisms

    Science.gov (United States)

    Starikovskaia, S. M.

    2014-09-01

    This review covers the results obtained in the period 2006-2014 in the field of plasma-assisted combustion, and in particular the results on ignition and combustion triggered or sustained by pulsed nanosecond discharges in different geometries. Some benefits of pulsed high voltage discharges for kinetic study and for applications are demonstrated. The necessity of and the possibility of building a particular kinetic mechanism of plasma-assisted ignition and combustion are discussed. The most sensitive regions of parameters for plasma-combustion kinetic mechanisms are selected. A map of the pressure and temperature parameters (P-T diagram) is suggested, to unify the available data on ignition delay times, ignition lengths and densities of intermediate species reported by different authors.

  19. Femtosecond and nanosecond pulsed laser deposition of silicon and germanium

    Energy Technology Data Exchange (ETDEWEB)

    Reenaas, Turid Worren [Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Lee, Yen Sian [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Chowdhury, Fatema Rezwana; Gupta, Manisha; Tsui, Ying Yin [Department of Electrical and Computer Engineering, University of Alberta (Canada); Tou, Teck Yong [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Ling [Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Kok, Soon Yie [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Shan, E-mail: seongshan@gmail.com [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-11-01

    Highlights: • Ge and Si were deposited by fs and ns laser at room temperature and at vacuum. • Ion of 10{sup 4} ms{sup −1} and 30–200 eV was obtained for ns ablation for Ge and Si. • Highly energetic ions of 10{sup 5} ms{sup −1} with 2–7 KeV were produced in fs laser ablation. • Nanocrystalline Si and Ge were deposited by using fs laser. • Nanoparticles < 10 nm haven been obtained by fs laser. - Abstract: 150 fs Ti:Sapphire laser pulsed laser deposition of Si and Ge were compared to a nanosecond KrF laser (25 ns). The ablation thresholds for ns lasers were about 2.5 J cm{sup −2} for Si and 2.1 J cm{sup −2} for Ge. The values were about 5–10 times lower when fs laser were used. The power densities were 10{sup 8}–10{sup 9} W cm{sup −2} for ns but 10{sup 12} W cm{sup −2} for fs. By using an ion probe, the ions emission at different fluence were measured where the emitting ions achieving the velocity in the range of 7–40 km s{sup −1} and kinetic energy in the range of 30–200 eV for ns laser. The ion produced by fs laser was measured to be highly energetic, 90–200 km s{sup −1}, 2–10 KeV. Two ion peaks were detected above specific laser fluence for both ns and fs laser ablation. Under fs laser ablation, the films were dominated by nano-sized crystalline particles, drastically different from nanosecond pulsed laser deposition where amorphous films were obtained. The ions characteristics and effects of pulse length on the properties of the deposited films were discussed.

  20. Modeling of plasma chemical processes in the artificial ionized layer in the upper atmosphere by the nanosecond corona discharge

    Science.gov (United States)

    Vikharev, A. L.; Gorbachev, A. M.; Ivanov, O. A.; Kolisko, A. L.; Litvak, A. G.

    1993-08-01

    The plasma chemical processes in the corona discharge formed in air by a series of high voltage pulses of nanosecond duration are investigated experimentally. The experimental conditions (reduced electric field, duration and repetition frequency of the pulses, gas pressure in the chamber) modeled the regime of creation of the artificial ionized layer (AIL) in the upper atmosphere by a nanosecond microwave discharge. It was found that in a nanosecond microwave discharge predominantly generation of ozone occurs, and that the production of nitrogen dioxide is not large. The energy expenditures for the generation of one O 3 molecule were about 15 eV. On the basis of the experimental results the prognosis of the efficiency of ozone generation in AIL was made.

  1. Electrosensitization Increases Antitumor Effectiveness of Nanosecond Pulsed Electric Fields In Vivo.

    Science.gov (United States)

    Muratori, Claudia; Pakhomov, Andrei G; Heller, Loree; Casciola, Maura; Gianulis, Elena; Grigoryev, Sergey; Xiao, Shu; Pakhomova, O N

    2017-01-01

    Nanosecond pulsed electric fields are emerging as a new modality for tissue and tumor ablation. We previously reported that cells exposed to pulsed electric fields develop hypersensitivity to subsequent pulsed electric field applications. This phenomenon, named electrosensitization, is evoked by splitting the pulsed electric field treatment in fractions (split-dose treatments) and causes in vitro a 2- to 3-fold increase in cytotoxicity. The aim of this study was to show the benefit of split-dose treatments for in vivo tumor ablation by nanosecond pulsed electric field. KLN 205 squamous carcinoma cells were embedded in an agarose gel or grown subcutaneously as tumors in mice. Nanosecond pulsed electric field ablations were produced using a 2-needle probe with a 6.5-mm interelectrode distance. In agarose gel, splitting a pulsed electric field dose of 300, 300-ns pulses (20 Hz, 4.4-6.4 kV) in 2 equal fractions increased cell death up to 3-fold compared to single-train treatments. We then compared the antitumor effectiveness of these treatments in vivo. At 24 hours after treatment, sensitizing tumors by a split-dose pulsed electric field exposure (150 + 150, 300-ns pulses, 20 Hz, 6.4 kV) caused a 4- and 2-fold tumor volume reduction as compared to sham and single-train treatments, respectively. Tumor volume reduction that exceeds 75% was 43% for split-dose-treated animals compared to only 12% for single-dose treatments. The difference between the 2 experimental groups remained statistically significant for at least 1 week after the treatment. The results show that electrosensitization occurs in vivo and can be exploited to assist in vivo cancer ablation.

  2. Studies on laser material processing with nanosecond and sub-nanosecond and picosecond and sub-picosecond pulses

    Science.gov (United States)

    Zhang, Jie; Tao, Sha; Wang, Brian; Zhao, Jay

    2016-03-01

    In this paper, laser ablation of widely used metal (Al, Cu. stainless-steel), semiconductor (Si), transparent material (glass, sapphire), ceramic (Al2O3, AlN) and polymer (PI, PMMA) in industry were systematically studied with pulse width from nanosecond (5-100ns), picosecond (6-10ps) to sub-picosecond (0.8-0.95ps). A critical damage zone (CDZ) of up to 100um with ns laser, efficiency were also investigated. This is to explore how to provide industry users the best laser solution for device micro-fabrication with best price. Our studies of cutting and drilling with ns, ps, and sub-ps lasers indicate that it is feasible to achieve user accepted quality and speed with cost-effective and reliable laser by optimizing processing conditions.

  3. Sub-nanosecond lasers for cosmetics and dermatology

    Science.gov (United States)

    Tarasov, Aleksandr A.; Chu, Hong

    2018-02-01

    We report about the development of two new subnanosecond solid-state laser models for application in dermatology and cosmetics. One model uses subnanosecond Nd: YAG microchip laser as a master oscillator and includes Nd: YAG double- and single-pass amplifiers. At 10 Hz this laser produces more than 600 mJ pulse energy with duration 500 +/- 5 ps. Another model (under development) is gain-switched Ti: Sapphire laser with short cavity. This laser produces 200 mJ, 560 ps pulses at 790 nm and uses standard Q-Switched Nd: YAG laser with nanosecond pulse duration as a pumping sourse.

  4. Physics of high intensity nanosecond electron source

    International Nuclear Information System (INIS)

    Herrera-Gomez, A.; Spicer, W.E.

    1993-08-01

    A new high-intensity, short-time electron source is now being used at the Stanford Linear Accelerator Center (SLAC). Using a GaAs negative affinity semiconductor in the construction of the cathode, it is possible to fulfill operation requirements such as peak currents of tens of amperes, peak widths of the order of nanoseconds, hundreds of hours of operation stability, and electron spin polarization. The cathode is illuminated with high intensity laser pulses, and photoemitted electrons constitute the yield. Because of the high currents, some nonlinear effects are present. Very noticeable is the so-called Charge Limit (CL) effect, which consists of a limit on the total charge in each pulse-that is, the total bunch charge stops increasing as the light pulse total energy increases. In this paper, we explain the mechanism of the CL and how it is caused by the photovoltaic effect. Our treatment is based on the Three-Step model of photoemission. We relate the CL to the characteristics of the surface and bulk of the semiconductor, such as doping, band bending, surface vacuum level, and density of surface states. We also discuss possible ways to prevent the Char's Level effect

  5. Hydrophobic treatment on polymethylmethacrylate surface by nanosecond-pulse DBDs in CF{sub 4} at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Cheng [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Zhou, Yang [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Shao, Tao, E-mail: st@mail.iee.ac.cn [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Xie, Qing [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Baoding 071003 (China); Xu, Jiayu [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Wenjin [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-08-30

    Highlights: • Increase in hydrophobicity on PMMA is achieved after the DBD treatment in CF{sub 4}, and the water contact angle can increase from 68° to 100° after treatment. • Nanosecond-pulse DBD is used for the surface treatment and the power density is about 114.8 mW/cm{sup 2}. • The effects of applied voltage, CF{sub 4} flow, and time on plasma treatment are investigated. • Plasma treatment causes morphological change, significantly increases the roughness of the surface, and introduces fluorine-containing groups into the polymethylmethacrylate surface. • Hydrophobic behavior of the treated PMMA surface is slightly affected by the aging effect. - Abstract: Nanosecond-pulse dielectric barrier discharge (DBD) can provide non-thermal plasmas with extremely high energy and high density, which can result in a series of complicated physical and chemical reactions in the surface treatment of polymers. Therefore, in this paper, hydrophobic treatment of polymethylmethacrylate (PMMA) surface is conducted by nanosecond-pulse DBD in carbon tetrafluoride (CF{sub 4}) at atmospheric pressure. Investigations on surface morphology and chemical composition before and after the DBD treatment in CF{sub 4} are conducted with the contact angle measurement, atomic force microscope, Fourier transform infrared spectroscopy, and X-ray photoelectron spectrometer. The effects of the applied voltage, CF{sub 4} flow rate, and treatment time on the hydrophobic modification are studied. Results show that the contact angles of the treated PMMA surface increases with the applied voltage, and it could be greatly affected by the CF{sub 4} flow rate and the treatment time. The water contact angle can increase from 68° to 100° after the treatment. Furthermore, both surface morphology and chemical composition of the PMMA samples are changed. Both the increase of the surface roughness and the occurrence of fluorine-containing functional groups on the PMMA surface treated by DBD in CF

  6. Performance of the Fitch generator in a nanosecond electron accelerator

    International Nuclear Information System (INIS)

    Chernyj, V.V.

    1976-01-01

    The operation of the Fitch generator in the nanosecond electron accelerator is discussed. The operating principle of the generator is based on the inversion of the voltage at the storage capacitances. Only one discharger is employed in the discharge circuit of the generator which provides for decreasing the generator impedance to 24 Ohms. The maximum accelerating voltage equals 0.6 MV

  7. Long-lived nanosecond spin coherence in high-mobility 2DEGs confined in double and triple quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Ullah, S.; Gusev, G. M.; Hernandez, F. G. G., E-mail: felixggh@if.usp.br [Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, CEP 05315-970 São Paulo, SP (Brazil); Bakarov, A. K. [Institute of Semiconductor Physics and Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

    2016-06-07

    We investigated the spin coherence of high-mobility two-dimensional electron gases confined in multilayer GaAs quantum wells. The dynamics of the spin polarization was optically studied using pump-probe techniques: time-resolved Kerr rotation and resonant spin amplification. For double and triple quantum wells doped beyond the metal-to-insulator transition, the spin-orbit interaction was tailored by the sample parameters of structural symmetry (Rashba constant), width, and electron density (Dresselhaus linear and cubic constants) which allow us to attain long dephasing times in the nanoseconds range. The determination of the scales, namely, transport scattering time, single-electron scattering time, electron-electron scattering time, and spin polarization decay time further supports the possibility of using n-doped multilayer systems for developing spintronic devices.

  8. Plasma surface treatment to improve surface charge accumulation and dissipation of epoxy resin exposed to DC and nanosecond-pulse voltages

    Science.gov (United States)

    Zhang, Cheng; Lin, Haofan; Zhang, Shuai; Xie, Qin; Ren, Chengyan; Shao, Tao

    2017-10-01

    In this paper, deposition by non-thermal plasma is used as a surface modification technique to change the surface characteristics of epoxy resin exposed to DC and nanosecond-pulse voltages. The corresponding surface characteristics in both cases of DC and nanosecond-pulse voltages before and after the modification are compared and investigated. The measurement of the surface potential provides the surface charge distribution, which is used to show the accumulation and dissipation process of the surface charges. Morphology observations, chemical composition and electrical parameters measurements are used to evaluate the treatment effects. The experimental results show that, before the plasma treatment, the accumulated surface charges in the case of the DC voltage are more than that in the case of the nanosecond-pulse voltage. Moreover, the decay rate of the surface charges for the DC voltage is higher than that for the nanosecond-pulse voltage. However, the decay rate is no more than 41% after 1800 s for both types of voltages. After the plasma treatment, the maximum surface potentials decrease to 57.33% and 32.57% of their values before treatment for the DC and nanosecond-pulse voltages, respectively, indicating a decrease in the accumulated surface charges. The decay rate exceeds 90% for both types of voltages. These changes are mainly attributed to a change in the surface nanostructure, an increase in conductivity, and a decrease in the depth of energy level.

  9. Plasma surface treatment to improve surface charge accumulation and dissipation of epoxy resin exposed to DC and nanosecond-pulse voltages

    International Nuclear Information System (INIS)

    Zhang, Cheng; Lin, Haofan; Zhang, Shuai; Ren, Chengyan; Shao, Tao; Xie, Qin

    2017-01-01

    In this paper, deposition by non-thermal plasma is used as a surface modification technique to change the surface characteristics of epoxy resin exposed to DC and nanosecond-pulse voltages. The corresponding surface characteristics in both cases of DC and nanosecond-pulse voltages before and after the modification are compared and investigated. The measurement of the surface potential provides the surface charge distribution, which is used to show the accumulation and dissipation process of the surface charges. Morphology observations, chemical composition and electrical parameters measurements are used to evaluate the treatment effects. The experimental results show that, before the plasma treatment, the accumulated surface charges in the case of the DC voltage are more than that in the case of the nanosecond-pulse voltage. Moreover, the decay rate of the surface charges for the DC voltage is higher than that for the nanosecond-pulse voltage. However, the decay rate is no more than 41% after 1800 s for both types of voltages. After the plasma treatment, the maximum surface potentials decrease to 57.33% and 32.57% of their values before treatment for the DC and nanosecond-pulse voltages, respectively, indicating a decrease in the accumulated surface charges. The decay rate exceeds 90% for both types of voltages. These changes are mainly attributed to a change in the surface nanostructure, an increase in conductivity, and a decrease in the depth of energy level. (paper)

  10. Outlook for the use of microsecond plasma opening switches to generate high-power nanosecond current pulses

    International Nuclear Information System (INIS)

    Dolgachev, G.I.; Maslennikov, D.D.; Ushakov, A.G.

    2006-01-01

    Paper deals with a phenomenon of current breaking in a conducting plasma volume of plasma opening switchers with a nanosecond time of energy initiation and their application in high-power generators. One determined the conditions to ensure megavolt voltages under the erosion mode making use of external applied magnetic field to ensure magnetic insulation of gap of plasma opening switchers. One studied the peculiar features of application of plasma opening switchers under 5-6 MV voltages to ensure X-ray and gamma-radiation pulses [ru

  11. New insights into the complex photoluminescence behaviour of titanium white pigments

    NARCIS (Netherlands)

    van Driel, B.A.; Artesani, A.; van den Berg, Klaas Jan; Dik, J.; Mosca, S.; Rossenaar, B.; Hoekstra, J.; Davies, A.; Nevin, A.; Valentini, G.; Comelli, D.

    2018-01-01

    This work reports the analysis of the time-resolved photoluminescence behaviour on the nanosecond and microsecond time scale of fourteen historical and contemporary titanium white pigments. The pigments were produced with different production methods and post-production treatments, giving rise to

  12. A note on supersonic flow control with nanosecond plasma actuator

    Science.gov (United States)

    Zheng, J. G.; Cui, Y. D.; Li, J.; Khoo, B. C.

    2018-04-01

    A concept study on supersonic flow control using nanosecond pulsed plasma actuator is conducted by means of numerical simulation. The nanosecond plasma discharge is characterized by the generation of a micro-shock wave in ambient air and a residual heat in the discharge volume arising from the rapid heating of near-surface gas by the quick discharge. The residual heat has been found to be essential for the flow separation control over aerodynamic bodies like airfoil and backward-facing step. In this study, novel experiment is designed to utilize the other flow feature from discharge, i.e., instant shock wave, to control supersonic flow through shock-shock interaction. Both bow shock in front of a blunt body and attached shock anchored at the tip of supersonic projectile are manipulated via the discharged-induced shock wave in an appropriate manner. It is observed that drag on the blunt body is reduced appreciably. Meanwhile, a lateral force on sharp-edged projectile is produced, which can steer the body and give it an effective angle of attack. This opens a promising possibility for extending the applicability of this flow control technique in supersonic flow regime.

  13. SPORT: A new sub-nanosecond time-resolved instrument to study swift heavy ion-beam induced luminescence - Application to luminescence degradation of a fast plastic scintillator

    Science.gov (United States)

    Gardés, E.; Balanzat, E.; Ban-d'Etat, B.; Cassimi, A.; Durantel, F.; Grygiel, C.; Madi, T.; Monnet, I.; Ramillon, J.-M.; Ropars, F.; Lebius, H.

    2013-02-01

    We developed a new sub-nanosecond time-resolved instrument to study the dynamics of UV-visible luminescence under high stopping power heavy ion irradiation. We applied our instrument, called SPORT, on a fast plastic scintillator (BC-400) irradiated with 27-MeV Ar ions having high mean electronic stopping power of 2.6 MeV/μm. As a consequence of increasing permanent radiation damages with increasing ion fluence, our investigations reveal a degradation of scintillation intensity together with, thanks to the time-resolved measurement, a decrease in the decay constant of the scintillator. This combination indicates that luminescence degradation processes by both dynamic and static quenching, the latter mechanism being predominant. Under such high density excitation, the scintillation deterioration of BC-400 is significantly enhanced compared to that observed in previous investigations, mainly performed using light ions. The observed non-linear behaviour implies that the dose at which luminescence starts deteriorating is not independent on particles' stopping power, thus illustrating that the radiation hardness of plastic scintillators can be strongly weakened under high excitation density in heavy ion environments.

  14. Measurement and deconvolution of detector response time for short HPM pulses: Part 1, Microwave diodes

    International Nuclear Information System (INIS)

    Bolton, P.R.

    1987-06-01

    A technique is described for measuring and deconvolving response times of microwave diode detection systems in order to generate corrected input signals typical of an infinite detection rate. The method has been applied to cases of 2.86 GHz ultra-short HPM pulse detection where pulse rise time is comparable to that of the detector; whereas, the duration of a few nanoseconds is significantly longer. Results are specified in terms of the enhancement of equivalent deconvolved input voltages for given observed voltages. The convolution integral imposes the constraint of linear detector response to input power levels. This is physically equivalent to the conservation of integrated pulse energy in the deconvolution process. The applicable dynamic range of a microwave diode is therefore limited to a smaller signal region as determined by its calibration

  15. Nanosecond laser ablation of target Al in a gaseous medium: explosive boiling

    Science.gov (United States)

    Mazhukin, V. I.; Mazhukin, A. V.; Demin, M. M.; Shapranov, A. V.

    2018-03-01

    An approximate mathematical description of the processes of homogeneous nucleation and homogeneous evaporation (explosive boiling) of a metal target (Al) under the influence of ns laser radiation is proposed in the framework of the hydrodynamic model. Within the continuum approach, a multi-phase, multi-front hydrodynamic model and a computational algorithm are designed to simulate nanosecond laser ablation of the metal targets immersed in gaseous media. The proposed approach is intended for modeling and detailed analysis of the mechanisms of heterogeneous and homogeneous evaporation and their interaction with each other. It is shown that the proposed model and computational algorithm allow modeling of interrelated mechanisms of heterogeneous and homogeneous evaporation of metals, manifested in the form of pulsating explosive boiling. Modeling has shown that explosive evaporation in metals is due to the presence of a near-surface temperature maximum. It has been established that in nanosecond pulsed laser ablation, such exposure regimes can be implemented in which phase explosion is the main mechanism of material removal.

  16. Femtosecond versus nanosecond laser machining: comparison of induced stresses and structural changes in silicon wafers

    International Nuclear Information System (INIS)

    Amer, M.S.; El-Ashry, M.A.; Dosser, L.R.; Hix, K.E.; Maguire, J.F.; Irwin, Bryan

    2005-01-01

    Laser micromachining has proven to be a very successful tool for precision machining and microfabrication with applications in microelectronics, MEMS, medical device, aerospace, biomedical, and defense applications. Femtosecond (FS) laser micromachining is usually thought to be of minimal heat-affected zone (HAZ) local to the micromachined feature. The assumption of reduced HAZ is attributed to the absence of direct coupling of the laser energy into the thermal modes of the material during irradiation. However, a substantial HAZ is thought to exist when machining with lasers having pulse durations in the nanosecond (NS) regime. In this paper, we compare the results of micromachining a single crystal silicon wafer using a 150-femtosecond and a 30-nanosecond lasers. Induced stress and amorphization of the silicon single crystal were monitored using micro-Raman spectroscopy as a function of the fluence and pulse duration of the incident laser. The onset of average induced stress occurs at lower fluence when machining with the femtosecond pulse laser. Induced stresses were found to maximize at fluence of 44 J cm -2 and 8 J cm -2 for nanosecond and femtosecond pulsed lasers, respectively. In both laser pulse regimes, a maximum induced stress is observed at which point the induced stress begins to decrease as the fluence is increased. The maximum induced stress was comparable at 2.0 GPa and 1.5 GPa for the two lasers. For the nanosecond pulse laser, the induced amorphization reached a plateau of approximately 20% for fluence exceeding 22 J cm -2 . For the femtosecond pulse laser, however, induced amorphization was approximately 17% independent of the laser fluence within the experimental range. These two values can be considered nominally the same within experimental error. For femtosecond laser machining, some effect of the laser polarization on the amount of induced stress and amorphization was also observed

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

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, K. V. [Moscow State Pedagogical University, 1 Malaya Pirogovskaya St., 119435 Moscow (Russian Federation); CJSC “Superconducting Nanotechnology” (Scontel), 5/22-1 Rossolimo St., 119021 Moscow (Russian Federation); National Research University Higher School of Economics, Moscow Institute of Electronics and Mathematics, 34 Tallinskaya St., 109028 Moscow (Russian Federation); Divochiy, A. V.; Karpova, U. V.; Morozov, P. V. [CJSC “Superconducting Nanotechnology” (Scontel), 5/22-1 Rossolimo St., 119021 Moscow (Russian Federation); Vakhtomin, Yu. B.; Seleznev, V. A. [Moscow State Pedagogical University, 1 Malaya Pirogovskaya St., 119435 Moscow (Russian Federation); CJSC “Superconducting Nanotechnology” (Scontel), 5/22-1 Rossolimo St., 119021 Moscow (Russian Federation); Sidorova, M. V. [Moscow State Pedagogical University, 1 Malaya Pirogovskaya St., 119435 Moscow (Russian Federation); Zotova, A. N.; Vodolazov, D. Yu. [Institute for Physics of Microstructure, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, 603950 Nizhny Novgorod (Russian Federation)

    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 R{sub n}, which appears after photon absorption, on its kinetic inductance L{sub k} and, hence, on the length of the detector. This conclusion is confirmed by our calculations in the framework of two temperature model.

  18. A simple sub-nanosecond ultraviolet light pulse generator with high repetition rate and peak power.

    Science.gov (United States)

    Binh, P H; Trong, V D; Renucci, P; Marie, X

    2013-08-01

    We present a simple ultraviolet sub-nanosecond pulse generator using commercial ultraviolet light-emitting diodes with peak emission wavelengths of 290 nm, 318 nm, 338 nm, and 405 nm. The generator is based on step recovery diode, short-circuited transmission line, and current-shaping circuit. The narrowest pulses achieved have 630 ps full width at half maximum at repetition rate of 80 MHz. Optical pulse power in the range of several hundreds of microwatts depends on the applied bias voltage. The bias voltage dependences of the output optical pulse width and peak power are analysed and discussed. Compared to commercial UV sub-nanosecond generators, the proposed generator can produce much higher pulse repetition rate and peak power.

  19. Rise time reduction of thermal actuators operated in air and water through optimized pre-shaped open-loop driving

    International Nuclear Information System (INIS)

    Larsen, T; Doll, J C; Loizeau, F; Pruitt, B L; Hosseini, N; Fantner, G E; Peng, A W; Ricci, A J

    2017-01-01

    Electrothermal actuators have many advantages compared to other actuators used in micro-electro-mechanical systems (MEMS). They are simple to design, easy to fabricate and provide large displacements at low voltages. Low voltages enable less stringent passivation requirements for operation in liquid. Despite these advantages, thermal actuation is typically limited to a few kHz bandwidth when using step inputs due to its intrinsic thermal time constant. However, the use of pre-shaped input signals offers a route for reducing the rise time of these actuators by orders of magnitude. We started with an electrothermally actuated cantilever having an initial 10–90% rise time of 85 μ s in air and 234 μ s in water for a standard open-loop step input. We experimentally characterized the linearity and frequency response of the cantilever when operated in air and water, allowing us to obtain transfer functions for the two cases. We used these transfer functions, along with functions describing desired reduced rise-time system responses, to numerically simulate the required input signals. Using these pre-shaped input signals, we improved the open-loop 10–90% rise time from 85 μ s to 3 μ s in air and from 234 μ s to 5 μ s in water, an improvement by a factor of 28 and 47, respectively. Using this simple control strategy for MEMS electrothermal actuators makes them an attractive alternative to other high speed micromechanical actuators such as piezoelectric stacks or electrostatic comb structures which are more complex to design, fabricate, or operate. (paper)

  20. Rise Time Reduction of Thermal Actuators Operated in Air and Water through Optimized Pre-Shaped Open-Loop Driving.

    Science.gov (United States)

    Larsen, T; Doll, J C; Loizeau, F; Hosseini, N; Peng, A W; Fantner, G; Ricci, A J; Pruitt, B L

    2017-01-01

    Electrothermal actuators have many advantages compared to other actuators used in Micro-Electro-Mechanical Systems (MEMS). They are simple to design, easy to fabricate and provide large displacements at low voltages. Low voltages enable less stringent passivation requirements for operation in liquid. Despite these advantages, thermal actuation is typically limited to a few kHz bandwidth when using step inputs due to its intrinsic thermal time constant. However, the use of pre-shaped input signals offers a route for reducing the rise time of these actuators by orders of magnitude. We started with an electrothermally actuated cantilever having an initial 10-90% rise time of 85 μs in air and 234 μs in water for a standard open-loop step input. We experimentally characterized the linearity and frequency response of the cantilever when operated in air and water, allowing us to obtain transfer functions for the two cases. We used these transfer functions, along with functions describing desired reduced rise-time system responses, to numerically simulate the required input signals. Using these pre-shaped input signals, we improved the open-loop 10-90% rise time from 85 μs to 3 μs in air and from 234 μs to 5 μs in water, an improvement by a factor of 28 and 47, respectively. Using this simple control strategy for MEMS electrothermal actuators makes them an attractive alternative to other high speed micromechanical actuators such as piezoelectric stacks or electrostatic comb structures which are more complex to design, fabricate, or operate.

  1. Plasma-Enhanced Combustion of Hydrocarbon Fuels and Fuel Blends Using Nanosecond Pulsed Discharges

    Energy Technology Data Exchange (ETDEWEB)

    Cappelli, Mark; Mungal, M Godfrey

    2014-10-28

    This project had as its goals the study of fundamental physical and chemical processes relevant to the sustained premixed and non-premixed jet ignition/combustion of low grade fuels or fuels under adverse flow conditions using non-equilibrium pulsed nanosecond discharges.

  2. Temporal shaping of nanosecond CO2 laser pulses in multiphoton saturable absorbers

    International Nuclear Information System (INIS)

    Haglund, R.F. Jr.

    1981-01-01

    It was shown that substantial temporal distortion of nanosecond 10.6 μm laser pulses occurs in traversing multiphoton saturable absorbers. The risetime and pulse delay effects appear to depend both on fluence and wavelength, and to be qualitatively consistent with predictions of a simple two-level absorption model

  3. High resolution selective multilayer laser processing by nanosecond laser ablation of metal nanoparticle films

    International Nuclear Information System (INIS)

    Ko, Seung H.; Pan Heng; Hwang, David J.; Chung, Jaewon; Ryu, Sangil; Grigoropoulos, Costas P.; Poulikakos, Dimos

    2007-01-01

    Ablation of gold nanoparticle films on polymer was explored using a nanosecond pulsed laser, with the goal to achieve feature size reduction and functionality not amenable with inkjet printing. The ablation threshold fluence for the unsintered nanoparticle deposit was at least ten times lower than the reported threshold for the bulk film. This could be explained by the combined effects of melting temperature depression, lower conductive heat transfer loss, strong absorption of the incident laser beam, and the relatively weak bonding between nanoparticles. The ablation physics were verified by the nanoparticle sintering characterization, ablation threshold measurement, time resolved ablation plume shadowgraphs, analysis of ablation ejecta, and the measurement and calculation of optical properties. High resolution and clean feature fabrication with small energy and selective multilayer processing are demonstrated

  4. Spectroscopic characteristics of H-alpha/O-I atomic lines generated by nanosecond pulsed corona-like discharge in deionized water

    Czech Academy of Sciences Publication Activity Database

    Pongrác, Branislav; Šimek, Milan; Člupek, Martin; Babický, Václav; Lukeš, Petr

    2018-01-01

    Roč. 51, č. 12 (2018), č. článku 124001. ISSN 0022-3727 R&D Projects: GA ČR(CZ) GA15-12987S Institutional support: RVO:61389021 Keywords : underwater discharge * nanosecond pulsed discharge * time-resolved emission spectroscopy Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.588, year: 2016 http://iopscience.iop.org/article/10.1088/1361-6463/aaabb1/meta

  5. Efficient temporal compression of coherent nanosecond pulses in compact SBS generator-amplifier setup

    NARCIS (Netherlands)

    Schiemann, S.; Ubachs, W.M.G.; Hogervorst, W.

    1997-01-01

    A pulse compressor based on stimulated Brillouin scattering (SBS) in liquids is experimentally and theoretically investigated. It allows for the compression of Fourier-transform limited nanosecond pulses of several hundreds of millijoules of energy with both high conversion efficiency and a high

  6. Nano-Second Isomers in Neutron-Rich Ni Region Produced by Deep-Inelastic Collisions

    International Nuclear Information System (INIS)

    Ishii, T.; Asai, M.; Matsuda, M.; Ichikawa, S.; Makishima, A.; Hossain, I.; Kleinheinz, P.; Ogawa, M.

    2001-01-01

    Nuclear structure of the doubly magic 68 Ni and its neighbors has been studied by spectroscopic techniques. Developing a new instrument isomer-scope, we have measured γ rays from nano-second isomers produced in heavy-ion deep-inelastic collisions with great sensitivity. (author)

  7. A thermal model for nanosecond pulsed laser ablation of aluminum

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2017-07-01

    Full Text Available In order to simulate the nanosecond pulsed laser ablation of aluminum, a novel model was presented for the target ablation and plume expansion. The simulation of the target ablation was based on one-dimensional heat conduction, taking into account temperature dependent material properties, phase transition, dielectric transition and phase explosion. While the simulation of the plume expansion was based on one-dimensional gas-dynamical equation, taking into account ionization, plume absorption and shielding. By coupling the calculations of the target ablation and plume expansion, the characteristics of the target and plume were obtained. And the calculated results were in good agreement with the experimental data, in terms of ablation threshold and depth within the fluence range of the tested laser. Subsequently, investigations were carried out to analyze the mechanisms of nanosecond pulsed laser ablation. The calculated results showed that the maximum surface temperature remained at about 90% of the critical temperature (0.9Tc due to phase explosion. Moreover, the plume shielding has significant effects on the laser ablation, and the plume shielding proportion increase as the laser fluence increasing. The ambient pressure belows 100 Pa is more suitable for laser ablation, which can obtained larger ablation depth.

  8. The second phase of bipolar, nanosecond-range electric pulses determines the electroporation efficiency.

    Science.gov (United States)

    Pakhomov, Andrei G; Grigoryev, Sergey; Semenov, Iurii; Casciola, Maura; Jiang, Chunqi; Xiao, Shu

    2018-03-29

    Bipolar cancellation refers to a phenomenon when applying a second electric pulse reduces ("cancels") cell membrane damage by a preceding electric pulse of the opposite polarity. Bipolar cancellation is a reason why bipolar nanosecond electric pulses (nsEP) cause weaker electroporation than just a single unipolar phase of the same pulse. This study was undertaken to explore the dependence of bipolar cancellation on nsEP parameters, with emphasis on the amplitude ratio of two opposite polarity phases of a bipolar pulse. Individual cells (CHO, U937, or adult mouse ventricular cardiomyocytes (VCM)) were exposed to either uni- or bipolar trapezoidal nsEP, or to nanosecond electric field oscillations (NEFO). The membrane injury was evaluated by time-lapse confocal imaging of the uptake of propidium (Pr) or YO-PRO-1 (YP) dyes and by phosphatidylserine (PS) externalization. Within studied limits, bipolar cancellation showed little or no dependence on the electric field intensity, pulse repetition rate, chosen endpoint, or cell type. However, cancellation could increase for larger pulse numbers and/or for longer pulses. The sole most critical parameter which determines bipolar cancellation was the phase ratio: maximum cancellation was observed with the 2nd phase of about 50% of the first one, whereas a larger 2nd phase could add a damaging effect of its own. "Swapping" the two phases, i.e., delivering the smaller phase before the larger one, reduced or eliminated cancellation. These findings are discussed in the context of hypothetical mechanisms of bipolar cancellation and electroporation by nsEP. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Megavolt nanosecond generator with semiconductor current breaker

    CERN Document Server

    Bushlyakov, A I; Rukin, S N; Slovikovskij, B G; Timoshenkov, S P

    2002-01-01

    The heavy-current nanosecond generator with the pulse capacity up to 1.6 GW and output voltage of 0.5-1 MW is described. The generator contains four capacity storages, one induction storage and six solid body commutators: one thyristor, four magnetic commutators and a semiconductor current breaker on the SOS-diodes. The results of studies on the energy change-over efficiency through a semiconductor breaker by various external resistance loads as well as the results of the thermal and frequency tests are presented. It is established that selection of the optimal cooling system provides for the generator continuous mode of operation with the pulse sequence frequency from 300 Hz up to 850 Hz

  10. Investigation on the Factors Influencing Construction Time and Cost Overrun for High-Rise Building Projects In Penang

    Science.gov (United States)

    Nor Haslinda, A.; Xian, T. Wei; Norfarahayu, K.; Muhamad Hanafi, R.; Fikri, H. Muhammad

    2018-04-01

    Time and cost overruns have become one prominent issue for most construction projects around the world. Project costing and timeframe extension had been causing a lot of wastage and loss of opportunity for many parties involved. Therefore, this research was carried out to investigate the factors influencing time and cost overruns for high-rise construction projects in Penang, Malaysia. A set of questionnaires survey was distributed to the project managers who had been or currently involved in the high-rise building projects in Penang to get their input and perceptions for each factor identified as well as its frequency of occurrence. In order to rank all the factors gathered, the mean index of the most distinguishing factors and its frequency of occurrence were multiplied to get the severity index. The results revealed that for time overrun, the most predominant causes were due to design changes, inadequate planning and scheduling and poor labor productivity. Meanwhile, the predominant causes of cost overrun were poor pre-construction budget and material cost planning, inaccurate quantity take-off and materials cost increased by inflation. The significance of establishing the issues related to time and cost overruns for the high-rise building construction project is to provide a greater insight and understanding on the causes of delays, particularly among the main project players: contractors, client, and consultants.

  11. Synthesis of pure ozone by nanosecond discharge at cryogenic temperatures

    International Nuclear Information System (INIS)

    Amirov, R.H.; Asinovsky, E.I.; Samoilov, I.S.

    1996-01-01

    Synthesis of pure ozone by nanosecond discharge at cryogenic temperatures was experimentally examined. The average ozone concentration in the volume of the discharge tube was less at cryogenic temperatures than at room temperatures. The production of condensed ozone have been determined by measuring the ozone concentration when the walls was heated and ozone evaporated. The energy yield of ozone generation at cryogenic temperatures has been calculated. The maximum value was 200 g/kWh

  12. Nanosecond pulse-width electron diode based on dielectric wall accelerator technology

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Quantang, E-mail: zhaoquantang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Z.M.; Yuan, P.; Cao, S.C.; Shen, X.K.; Jing, Y. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Yu, C.S. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Z.P.; Liu, M.; Xiao, R.Q. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zong, Y.; Wang, Y.R. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, H.W. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2013-11-21

    An electron diode using a short section of dielectric wall accelerator (DWA) has been under development at the Institute of Modern Physics (IMP), Chinese Academy of Sciences. Tests have been carried out with spark gap switches triggered by lasers. The stack voltage efficiency of a four-layer of Blumleins reached about 60–70% with gas filled spark gap switching. The generated pulse voltage of peak amplitude of 23 kV and pulse width of 5 ns is used to extract and accelerate an electron beam of 320 mA, measured by a fast current transformer. A nanosecond pulse width electron diode was achieved successfully. Furthermore, the principle of a DWA is well proven and the development details and discussions are presented in this article. -- Highlights: •The key technology of DWA, including switches and pulse forming lines were studied. •The SiC PCSS obtained from Shanghai Institute were tested. •Two layers ZIP lines (new structure) and four layers Blumlein lines were studied with laser triggered spark gap switches. •A nanosecond pulse-width electron diode based on DWA technologies is achieved and studied experimentally. •The principle of DWA is also proved by the diode.

  13. High-speed 2 × 2 silicon-based electro-optic switch with nanosecond switch time

    International Nuclear Information System (INIS)

    Xue-Jun, Xu; Shao-Wu, Chen; Hai-Hua, Xu; Yang, Sun; Yu-De, Yu; Jin-Zhong, Yu; Qi-Ming, Wang

    2009-01-01

    A 2 × 2 electro-optic switch is experimentally demonstrated using the optical structure of a Mach–Zehnder interferometer (MZI) based on a submicron rib waveguide and the electrical structure of a PIN diode on silicon-on-insulator (SOI). The switch behaviour is achieved through the plasma dispersion effect of silicon. The device has a modulation arm of 1 mm in length and cross-section of 400 nm×340 nm. The measurement results show that the switch has a V π L π figure of merit of 0.145 V·cm and the extinction ratios of two output ports and cross talk are 40 dB, 28 dB and −28 dB, respectively. A 3 dB modulation bandwidth of 90 MHz and a switch time of 6.8 ns for the rise edge and 2.7 ns for the fall edge are also demonstrated

  14. THE INFLUENCE OF NANOSECOND ELECTROMAGNETIC PULSES TO OBTAIN TIN AND THE PROPERTIES OF ITS ALLOYS

    Directory of Open Access Journals (Sweden)

    V. G. Komkov

    2012-01-01

    Full Text Available Experimentally found that the effect of nanosecond electromagnetic pulses to melt the charge, while the carbon thermal recovery of the tin ore, accelerates the formation of the metallic phase.

  15. Nanosecond pulsed laser induced self-organized nano-dots patterns on GaSb surface

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Yutaka, E-mail: yyoshida@cris.hokudai.ac.jp [Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, N8, W13, Kita-ku, Sapporo 060-8628, Hokkaido (Japan); Creative Research Institution Sousei, Hokkaido University, N21, W10, Kita-ku, Sapporo 001-0021, Hokkaido (Japan); Oosawa, Kazuya; Wajima, Jyunya; Watanabe, Seiichi [Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, N8, W13, Kita-ku, Sapporo 060-8628, Hokkaido (Japan); Matsuo, Yasutaka [Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Hokkaido (Japan); Kato, Takahiko [Hitachi Research Laboratory, Hitachi, Ltd., 7-1-1 Omika, Hitachi-shi 319-1292, Ibaraki-ken (Japan); Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, N8, W13, Kita-ku, Sapporo 060-8628, Hokkaido (Japan)

    2014-07-01

    We report a technique for formation of two-dimensional (2D) nanodot (ND) patterns on gaillium antimoide (GaSb) using a nanosecond pulsed laser irradiation with 532 nm wavelength. The patterns have formed because of the interference and the self-organization under energy deposition of the laser irradiation, which induced the growth of NDs on the local area. The NDs are grown and shrunken in the pattern by energy depositions. In the laser irradiation with average laser energy density of 35 mJ cm⁻², large and small NDs are formed on GaSb surface. The large NDs have grown average diameter from 160 to 200 nm with increase of laser pulses, and the small NDs have shrunken average diameter from 75 to 30 nm. The critical dot size is required about 107 nm for growth of the NDs in the patterns. Nanosecond pulsed laser irradiation can control the self-organized ND size on GaSb in air as a function of the laser pulses.

  16. Gold nanoshell photomodification under a single-nanosecond laser pulse accompanied by color-shifting and bubble formation phenomena

    International Nuclear Information System (INIS)

    Akchurin, Garif; Khlebtsov, Boris; Akchurin, Georgy; Tuchin, Valery; Zharov, Vladimir; Khlebtsov, Nikolai

    2008-01-01

    Laser-nanoparticle interaction is crucial for biomedical applications of lasers and nanotechnology to the treatment of cancer or pathogenic microorganisms. We report on the first observation of laser-induced coloring of gold nanoshell solution after a one nanosecond pulse and an unprecedentedly low bubble formation (as the main mechanism of cancer cell killing) threshold at a laser fluence of about 4 mJ cm -2 , which is safe for normal tissue. Specifically, silica/gold nanoshell (140/15 nm) suspensions were irradiated with a single 4 ns (1064 nm) or 8 ns (900 nm) laser pulse at fluences ranging from 0.1 mJ cm -2 to 50 J cm -2 . Solution red coloring was observed by the naked eye confirmed by blue-shifting of the absorption spectrum maximum from the initial 900 nm for nanoshells to 530 nm for conventional colloidal gold nanospheres. TEM images revealed significant photomodification of nanoparticles including complete fragmentation of gold shells, changes in silica core structure, formation of small 20-30 nm isolated spherical gold nanoparticles, gold nanoshells with central holes, and large and small spherical gold particles attached to a silica core. The time-resolved monitoring of bubble formation phenomena with the photothermal (PT) thermolens technique demonstrated that after application of a single 8 ns pulse at fluences 5-10 mJ cm -2 and higher the next pulse did not produce any PT response, indicating a dramatic decrease in absorption because of gold shell modification. We also observed a dependence of the bubble expansion time on the laser energy with unusually very fast PT signal rising (∼3.5 ns scale at 0.2 J cm -2 ). Application of the observed phenomena to medical applications is discussed, including a simple visual color test for laser-nanoparticle interaction

  17. Electric field measurements in a nanosecond pulse discharge by picosecond CARS/4-wave mixing

    Science.gov (United States)

    Goldberg, Ben; Shkurenkov, Ivan; Adamovich, Igor; Lempert, Walter

    2014-10-01

    Time-resolved electric field measurements in hydrogen by picosecond CARS/4-wave mixing are presented. Measurements are carried out in a high voltage nanosecond pulse discharge in hydrogen in plane-to-plane geometry, at pressures of up to several hundred Torr, and with a time resolution of 0.2 ns. Absolute calibration of the diagnostics is done using a sub-breakdown high voltage pulse of 12 kV/cm. A diffuse discharge is obtained by applying a peak high voltage pulse of 40 kV/cm between the electrodes. It is found that breakdown occurs at a lower field, 15--20 kV/cm, after which the field in the plasma is reduced rapidly due to plasma self shielding The experimental results are compared with kinetic modeling calculations, showing good agreement between the measured and the predicted electric field.

  18. A novel method of calculating the energy deposition curve of nanosecond pulsed surface dielectric barrier discharge

    International Nuclear Information System (INIS)

    He, Kun; Wang, Xinying; Lu, Jiayu; Cui, Quansheng; Pang, Lei; Di, Dongxu; Zhang, Qiaogen

    2015-01-01

    To obtain the energy deposition curve is very important in the fields to which nanosecond pulse dielectric barrier discharges (NPDBDs) are applied. It helps the understanding of the discharge physics and fast gas heating. In this paper, an equivalent circuit model, composed of three capacitances, is introduced and a method of calculating the energy deposition curve is proposed for a nanosecond pulse surface dielectric barrier discharge (NPSDBD) plasma actuator. The capacitance C d and the energy deposition curve E R are determined by mathematically proving that the mapping from C d to E R is bijective and numerically searching one C d that satisfies the requirement for E R to be a monotonically non-decreasing function. It is found that the value of capacitance C d varies with the amplitude of applied pulse voltage due to the change of discharge area and is dependent on the polarity of applied voltage. The bijectiveness of the mapping from C d to E R in nanosecond pulse volumetric dielectric barrier discharge (NPVDBD) is demonstrated and the feasibility of the application of the new method to NPVDBD is validated. This preliminarily shows a high possibility of developing a unified approach to calculate the energy deposition curve in NPDBD. (paper)

  19. Combination of microsecond and nanosecond pulsed electric field treatments for inactivation of Escherichia coli in water samples.

    Science.gov (United States)

    Žgalin, Maj Kobe; Hodžić, Duša; Reberšek, Matej; Kandušer, Maša

    2012-10-01

    Inactivation of microorganisms with pulsed electric fields is one of the nonthermal methods most commonly used in biotechnological applications such as liquid food pasteurization and water treatment. In this study, the effects of microsecond and nanosecond pulses on inactivation of Escherichia coli in distilled water were investigated. Bacterial colonies were counted on agar plates, and the count was expressed as colony-forming units per milliliter of bacterial suspension. Inactivation of bacterial cells was shown as the reduction of colony-forming units per milliliter of treated samples compared to untreated control. According to our results, when using microsecond pulses the level of inactivation increases with application of more intense electric field strengths and with number of pulses delivered. Almost 2-log reductions in bacterial counts were achieved at a field strength of 30 kV/cm with eight pulses and a 4.5-log reduction was observed at the same field strength using 48 pulses. Extending the duration of microsecond pulses from 100 to 250 μs showed no improvement in inactivation. Nanosecond pulses alone did not have any detectable effect on inactivation of E. coli regardless of the treatment time, but a significant 3-log reduction was achieved in combination with microsecond pulses.

  20. Enhancing cell proliferation by non-contact nanosecond PEF treatment of cell culture vials

    NARCIS (Netherlands)

    Bree, van J.W.M.; Geysen, J.J.G.; Pemen, A.J.M.

    2012-01-01

    The applicability of nanosecond pulsed electric fields (nsPEF) has been focused on killing of cells by means of direct contact between the nsPEF electrodes and tissue or liquid, such as in melanoma destruction [1] and sterilization of fluids. Here we present a novel, tabletop device that induces

  1. Pengaruh Variasi Jumlah Tembakan Nanosecond Pulsed Electric Fields (Nspefs Terhadap Ekspresi Gen Socs3 pada Sel Kanker Serviks Hela S3

    Directory of Open Access Journals (Sweden)

    Martina Kurnia Rohmah

    2017-12-01

    Abstract Nanosecond Pulsed Electric Fields (NsPEFs is bioelectric that was developed by electroporation technology. NsPEFs use high intensity in short time exposure (1 – 300 nanosecond. NsPEFs have biological effect and was developed in cancer therapy. In cervical cancer, viral protein of HPV depresses some tumor suppressors like Socs3 gene. This research aims to investigate the effect of short variation in Socs3 gene expression. HeLa S3 cells were cultured in α-MEM with FBS 10%. NsPEFs as much as 20 kV/cm and 80 nano seconds was exposure over HeLa S3 cell in 4 mm cuvette. Wave of NsPEFs was detected by high voltage probe in oscilloscope. NsPEFs was exposure at 0 (control, 5, 10, 20, 30, 40, 50, and 60 shots. Socs3 gene expression was analyzed using real time PCR and RT-PCR. Quantitative data was analyzed by Kolmogorov-Smirnov, Anova, and HSD Tuker (p<0.05. This research show that NsPEFs is significantly increase Socs3 gene expression (p=0.000. The optimal shot 20 and 30 shots increase Socs3 gene expression subsequently = 2.779 and = 3.105 times. This expression decrease in higher than 30 shots of NsPEFs exposure.   Keywords: NsPEFs, shot, expression, Socs3

  2. Luminescence rise time in self-activated PbWO4 and Ce-doped Gd3Al2Ga3O12 scintillation crystals

    CERN Document Server

    E. Auffray; A. Borisevich; V. Gulbinas; A. Fedorov; M. Korjik; M.T. Lucchini; V. Mechinsky; S. Nargelas; E. Songaila; G. Tamulaitis; A. Vaitkevičius; S. Zazubovich

    2016-01-01

    The time resolution of scintillation detectors of ionizing radiation is one of the key parameters sought for in the current and future high-energy physics experiments. This study is encouraged by the necessity to find novel detection methods enabling a sub-10-ps time resolution in scintillation detectors and is focused on the exploitation of fast luminescence rise front. Time-resolved photoluminescence (PL) spectroscopy and thermally stimulated luminescence techniques have been used to study two promising scintillators: self-activated lead tungstate (PWO, PbWO4) and Ce-doped gadolinium aluminum gallium garnet (GAGG, Gd3Al2Ga3O12). A sub-picosecond PL rise time is observed in PWO, while longer processes in the PL response in GAGG:Ce are detected and studied. The mechanisms responsible for the PL rise time in self-activated and doped scintillators are under discussion.

  3. Relativistic rise measurement by cluster counting method in time expansion chamber

    International Nuclear Information System (INIS)

    Rehak, P.; Walenta, A.H.

    1979-10-01

    A new approach to the measurement of the ionization energy loss for the charged particle identification in the region of the relativistic rise was tested experimentally. The method consists of determining in a special drift chamber (TEC) the number of clusters of the primary ionization. The method gives almost the full relativistic rise and narrower landau distribution. The consequences for a practical detector are discussed

  4. Computer network time synchronization the network time protocol

    CERN Document Server

    Mills, David L

    2006-01-01

    What started with the sundial has, thus far, been refined to a level of precision based on atomic resonance: Time. Our obsession with time is evident in this continued scaling down to nanosecond resolution and beyond. But this obsession is not without warrant. Precision and time synchronization are critical in many applications, such as air traffic control and stock trading, and pose complex and important challenges in modern information networks.Penned by David L. Mills, the original developer of the Network Time Protocol (NTP), Computer Network Time Synchronization: The Network Time Protocol

  5. Spin-on nanostructured silicon-silica film displaying room-temperature nanosecond lifetime photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Y.; Hatton, B.; Miguez, H.; Coombs, N.; Fournier-Bidoz, S.; Ozin, G.A. [Materials Chemistry Research Group, Department of Chemistry, Lash Miller Chemical Laboratories, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 (Canada); Grey, J.K.; Beaulac, R.; Reber, C. [Department of Chemistry, University of Montreal, Montreal, Quebec H3C 3J7 (Canada)

    2003-04-17

    A yellow transparent mesoporous silica film has been achieved by the incorporation of silicon nanoclusters into its channels. The resulting nanocomposite - fabricated using a combination of evaporation induced self- assembly and chemical vapor deposition - emits light brightly at visible wavelengths and has nanosecond radiative lifetimes at room temperature when excited by ultraviolet light (see Figure). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  6. Nanosecond Surface Microdischarges in Multilayer Structures

    Science.gov (United States)

    Dubinov, A. E.; Lyubimtseva, V. A.

    2018-05-01

    Multilayer structures in which nanosecond surface microdischarges are generated have been developed, fabricated, and investigated. In these structures, layers are made in the form of thin transparent films, and a plasma discharge channel is formed in thin spacings between the layers. Passage of the discharge channel from one layer into the neighboring layer is implemented via pre-fabricated microholes. Images of microdischarges were obtained which confirmed that their plasma channels are formed according to the route assigned by the holes. The route may follow a fairly complex scheme and have self-intersection points and portions in which the electrons are bound to move in opposition to the electric field. In studying the shape of channels in multilayer strictures, the authors have found a new physical effect which lies in the azimuthal self-orientation of the discharge channel as it passes from one microhole to another.

  7. Fast rise time IR detectors for lepton colliders

    International Nuclear Information System (INIS)

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

    2016-01-01

    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.

  8. OH density measured by PLIF in a nanosecond atmospheric pressure diffuse discharge in humid air under steep high voltage pulses

    Science.gov (United States)

    Ouaras, K.; Magne, L.; Pasquiers, S.; Tardiveau, P.; Jeanney, P.; Bournonville, B.

    2018-04-01

    The spatiotemporal distributions of the OH radical density are measured using planar laser induced fluorescence in the afterglow of a nanosecond diffuse discharge at atmospheric pressure in humid air. The diffuse discharge is generated between a pin and a grounded plate electrodes within a gap of 18 mm. The high voltage pulse applied to the pin ranges from 65 to 85 kV with a rise time of 2 ns. The specific electrical energy transferred to the gas ranges from 5 to 40 J l‑1. The influence of H2O concentration is studied from 0.5% to 1.5%. An absolute calibration of OH density is performed using a six-level transient rate equation model to simulate the dynamics of OH excitation by the laser, taking into account collisional processes during the optical pumping and the fluorescence. Rayleigh scattering measurements are used to achieve the geometrical part of the calibration. A local maximum of OH density is found in the pin area whatever the operating conditions. For 85 kV and 1% of H2O, this peak reaches a value of 2.0 × 1016 cm‑3 corresponding to 8% of H2O dissociation. The temporal decay of the spatially averaged OH density is found to be similar as in the afterglow of a homogeneous photo-triggered discharge for which a self-consistent modeling is done. These tools are then used to bring discussion elements on OH kinetics.

  9. Particle-in-cell modeling of the nanosecond field emission driven discharge in pressurized hydrogen

    Science.gov (United States)

    Levko, Dmitry; Yatom, Shurik; Krasik, Yakov E.

    2018-02-01

    The high-voltage field-emission driven nanosecond discharge in pressurized hydrogen is studied using the one-dimensional Particle-in-Cell Monte Carlo collision model. It is obtained that the main part of the field-emitted electrons becomes runaway in the thin cathode sheath. These runaway electrons propagate the entire cathode-anode gap, creating rather dense (˜1012 cm-3) seeding plasma electrons. In addition, these electrons initiate a streamer propagating through this background plasma with a speed ˜30% of the speed of light. Such a high streamer speed allows the self-acceleration mechanism of runaway electrons present between the streamer head and the anode to be realized. As a consequence, the energy of runaway electrons exceeds the cathode-anode gap voltage. In addition, the influence of the field emission switching-off time is analyzed. It is obtained that this time significantly influences the discharge dynamics.

  10. Laser induced fluorescence in nanosecond repetitively pulsed discharges for CO2 conversion

    Science.gov (United States)

    Martini, L. M.; Gatti, N.; Dilecce, G.; Scotoni, M.; Tosi, P.

    2018-01-01

    A CO2 nanosecond repetitively pulsed discharge (NRP) is a harsh environment for laser induced fluorescence (LIF) diagnostics. The difficulties arise from it being a strongly collisional system in which the gas composition, pressure and temperature, have quick and strong variations. The relevant diagnostic problems are described and illustrated through the application of LIF to the measurement of the OH radical in three different discharge configurations, with gas mixtures containing CO2 + H2O. These range from a dielectric barrier NRP with He buffer gas, a less hostile case in which absolute OH density measurement is possible, to an NRP in CO2+H2O, where the full set of drawbacks is at work. In the last case, the OH density measurement is not possible with laser pulses and detector time resolution in the ns time scale. Nevertheless, it is shown that with a proper knowledge of the collisional rate constants involved in the LIF process, a collisional energy transfer-LIF methodology is still applicable to deduce the gas composition from the analysis of LIF spectra.

  11. Damage caused by a nanosecond UV laser on a heated copper surface

    Energy Technology Data Exchange (ETDEWEB)

    Henč-Bartolić, V., E-mail: visnja.henc@fer.hr [University of Zagreb, Faculty of Electrical Engineering and Computing, Unska 3, 10000 Zagreb (Croatia); Bončina, T. [University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor (Slovenia); Jakovljević, S., E-mail: suzana.jakovljevic@fsb.hr [University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Ivana Lučića 5, 10002 Zagreb (Croatia); Panjan, P. [Jožef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Zupanič, F. [University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor (Slovenia)

    2016-08-15

    Highlights: • A Cu-plate was exposed to nanosecond UV laser with max. energy 1.1 J/cm{sup 2}. • Surface topography was studied on the cold and heated copper plate. • At room temperature, a crater formed, the melt was ejected from it. • Capillary waves formed in the vicinity of the crater at 360 °C. - Abstract: This work studied the effect of thin copper plate temperature on its surface morphology after irradiation using a pulsed nanosecond UV laser. The surface characteristics were investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam and stylus profilometry. When a target was at room temperature, a crater and the radial flow of molten Cu from the crater was observed. When the thin target was warm (about 360 °C ± 20 °C), a crater was smaller, and quasi-semicircular waves with the periodicity of around 3 μm appeared in its vicinity. The origin of the waves is Marangoni effect, causing thermocapillary waves, which in same occasions had a structure of final states of chaos in Rayleigh–Bénard convection.

  12. Visualization of nanosecond laser-induced dewetting, ablation and crystallization processes in thin silicon films

    Science.gov (United States)

    Qi, Dongfeng; Zhang, Zifeng; Yu, Xiaohan; Zhang, Yawen

    2018-06-01

    In the present work, nanosecond pulsed laser crystallization, dewetting and ablation of thin amorphous silicon films are investigated by time-resolved imaging. Laser pulses of 532 nm wavelength and 7 ns temporal width are irradiated on silicon film. Below the dewetting threshold, crystallization process happens after 400 ns laser irradiation in the spot central region. With the increasing of laser fluence, it is observed that the dewetting process does not conclude until 300 ns after the laser irradiation, forming droplet-like particles in the spot central region. At higher laser intensities, ablative material removal occurs in the spot center. Cylindrical rims are formed in the peripheral dewetting zone due to solidification of transported matter at about 500 ns following the laser pulse exposure.

  13. Luminescence rise time in self-activated PbWO{sub 4} and Ce-doped Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} scintillation crystals

    Energy Technology Data Exchange (ETDEWEB)

    Auffray, E. [CERN, Geneva (Switzerland); Augulis, R. [Center for Physical Sciences and Technology, Savanorių av. 231, Vilnius (Lithuania); Borisevich, A. [Research Institute for Nuclear Problems, Bobruiskaya str. 11, Minsk (Belarus); Gulbinas, V. [Center for Physical Sciences and Technology, Savanorių av. 231, Vilnius (Lithuania); Fedorov, A.; Korjik, M. [Research Institute for Nuclear Problems, Bobruiskaya str. 11, Minsk (Belarus); Lucchini, M.T. [CERN, Geneva (Switzerland); Mechinsky, V. [Research Institute for Nuclear Problems, Bobruiskaya str. 11, Minsk (Belarus); Nargelas, S. [Vilnius University, Universiteto str. 3, Vilnius (Lithuania); Songaila, E. [Center for Physical Sciences and Technology, Savanorių av. 231, Vilnius (Lithuania); Tamulaitis, G. [Vilnius University, Universiteto str. 3, Vilnius (Lithuania); Vaitkevičius, A., E-mail: augustas.vaitkevicius@ff.vu.lt [Vilnius University, Universiteto str. 3, Vilnius (Lithuania); Zazubovich, S. [Institute of Physics, University of Tartu, W. Ostwaldi Str. 1, Tartu (Estonia)

    2016-10-15

    The time resolution of scintillation detectors of ionizing radiation is one of the key parameters sought for in the current and future high-energy physics experiments. This study is encouraged by the necessity to find novel detection methods enabling a sub-10-ps time resolution in scintillation detectors and is focused on the exploitation of fast luminescence rise front. Time-resolved photoluminescence (PL) spectroscopy and thermally stimulated luminescence techniques have been used to study two promising scintillators: self-activated lead tungstate (PWO, PbWO{sub 4}) and Ce-doped gadolinium aluminum gallium garnet (GAGG, Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12}). A sub-picosecond PL rise time is observed in PWO, while longer processes in the PL response in GAGG:Ce are detected and studied. The mechanisms responsible for the PL rise time in self-activated and doped scintillators are under discussion. - Highlights: • Photoluminescence rise time is studied in two scintillators: PWO and GAGG:Ce. • Sub-picosecond photoluminescence rise time in PWO is observed for the first time. • A multicomponent luminescence rise edge is observed in GAGG:Ce. • The mechanisms behind luminescence kinetics in the crystals are under discussion.

  14. Nanosecond-resolved temperature measurements using magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wenbiao; Zhang, Pu [School of Automation, Huazhong University of Science and Technology, Wuhan 430074 (China); Liu, Wenzhong, E-mail: lwz7410@hust.edu.cn [School of Automation, Huazhong University of Science and Technology, Wuhan 430074 (China); Key Laboratory of Image Processing and Intelligent Control, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2016-05-15

    Instantaneous and noninvasive temperature measurements are important when laser thermotherapy or welding is performed. A noninvasive nanosecond-resolved magnetic nanoparticle (MNP) temperature measurement system is described in which a transient change in temperature causes an instantaneous change in the magnetic susceptibilities of the MNPs. These transient changes in the magnetic susceptibilities are rapidly recorded using a wideband magnetic measurement system with an upper frequency limit of 0.5 GHz. The Langevin function (the thermodynamic model characterizing the MNP magnetization process) is used to obtain the temperature information. Experiments showed that the MNP DC magnetization temperature-measurement system can detect a 14.4 ns laser pulse at least. This method of measuring temperature is likely to be useful for acquiring the internal temperatures of materials irradiated with lasers, as well as in other areas of research.

  15. Multiple pulse nanosecond laser induced damage threshold on hybrid mirrors

    Science.gov (United States)

    Vanda, Jan; Muresan, Mihai-George; Bilek, Vojtech; Sebek, Matej; Hanus, Martin; Lucianetti, Antonio; Rostohar, Danijela; Mocek, Tomas; Škoda, Václav

    2017-11-01

    So-called hybrid mirrors, consisting of broadband metallic surface coated with dielectric reflector designed for specific wavelength, becoming more important with progressing development of broadband mid-IR sources realized using parametric down conversion system. Multiple pulse nanosecond laser induced damage on such mirrors was tested by method s-on-1, where s stands for various numbers of pulses. We show difference in damage threshold between common protected silver mirrors and hybrid silver mirrors prepared by PVD technique and their variants prepared by IAD. Keywords: LIDT,

  16. Double nanosecond pulses generation in ytterbium fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Veiko, V. P.; Samokhvalov, A. A., E-mail: samokhvalov.itmo@gmail.com; Yakovlev, E. B.; Zhitenev, I. Yu.; Kliushin, A. N. [Saint-Petersburg State University of Information Technologies, Mechanics and Optics, Kronverksky Pr. 49, Saint Petersburg (Russian Federation); Lednev, V. N. [Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov Str., 38, Moscow (Russian Federation); National University of Science and Technology MISiS, Leninskyave., 4, Moscow (Russian Federation); Pershin, S. M. [Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov Str., 38, Moscow (Russian Federation)

    2016-06-15

    Double pulse generation mode for nanosecond ytterbium fiber laser was developed. Two sequential 60-200 ns laser pulses with variable delay between them were generated by acousto-optic modulator opening with continuous diode pumping. A custom radio frequency generator was developed to produce two sequential “opening” radio pulses with a delay of 0.2–1 μs. It was demonstrated that double pulse generation did not decrease the average laser power while providing the control over the laser pulse power profile. Surprisingly, a greater peak power in the double pulse mode was observed for the second laser pulse. Laser crater studies and plasma emission measurements revealed an improved efficiency of laser ablation in the double pulse mode.

  17. Absorption and luminescence of crystalline quartz under electron nanosecond irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Gritsenko, B P; Lisitsyn, V M; Stepanchuk, V N [Tomskij Politekhnicheskij Inst. (USSR)

    1981-02-01

    The purpose of the study is continuation of investigations of principal regularities of production and destruction of short-lived defects in quartz and accompanying luminescence under electron pulse irradiation. For investigation purposes samples of crystalline synthetic quartz have been used. The irradiation has been performed at 80-400 K temperatures by means of an electron pulse accelerator with parameters: electron flow pulse duration 10 ns, pulse current density up to 1000 A/cm/sup 2/, electron mean energy 200 keV. Temperature-time characteristics of absorption and luminescence spectrum are studied. It has been found that quartz irradiation by electron pulses of nanosecond duration leads to appearance of short-lived bands of optical absorption at 4.1 and 5.15 eV to which by kinetic parameters correspond luminescence bands at 2.6 and 3.1 eV, respectively. The enumerated absorption bands are induced by quartz irradiation independently of the prehistory and phase state of the sample and are caused obviously by intrinsic radiation defects. Possible models of such defects are suggested.

  18. Effect of parallel magnetic field on repetitively unipolar nanosecond pulsed dielectric barrier discharge under different pulse repetition frequencies

    Science.gov (United States)

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

    2018-03-01

    A magnetic field, with the direction parallel to the electric field, is applied to the repetitively unipolar positive nanosecond pulsed dielectric barrier discharge. The effect of the parallel magnetic field on the plasma generated between two parallel-plate electrodes in quiescent air is experimentally studied under different pulse repetition frequencies (PRFs). It is indicated that only the current pulse in the rising front of the voltage pulse occurs, and the value of the current is increased by the parallel magnetic field under different PRFs. The discharge uniformity is improved with the decrease in PRF, and this phenomenon is also observed in the discharge with the parallel magnetic field. By using the line-ratio technique of optical emission spectra, it is found that the average electron density and electron temperature under the considered PRFs are both increased when the parallel magnetic field is applied. The incremental degree of average electron density is basically the same under the considered PRFs, while the incremental degree of electron temperature under the higher-PRFs is larger than that under the lower-PRFs. All the above phenomena are explained by the effect of parallel magnetic field on diffusion and dissipation of electrons.

  19. Electrosensitization Increases Antitumor Effectiveness of Nanosecond Pulsed Electric Fields In Vivo

    OpenAIRE

    Muratori, Claudia; Pakhomov, Andrei G.; Heller, Loree; Casciola, Maura; Gianulis, Elena; Grigoryev, Sergey; Xiao, Shu; Pakhomova, O. N.

    2017-01-01

    Nanosecond pulsed electric fields are emerging as a new modality for tissue and tumor ablation. We previously reported that cells exposed to pulsed electric fields develop hypersensitivity to subsequent pulsed electric field applications. This phenomenon, named electrosensitization, is evoked by splitting the pulsed electric field treatment in fractions (split-dose treatments) and causes in vitro a 2- to 3-fold increase in cytotoxicity. The aim of this study was to show the benefit of split-d...

  20. Plume rise from multiple sources

    International Nuclear Information System (INIS)

    Briggs, G.A.

    1975-01-01

    A simple enhancement factor for plume rise from multiple sources is proposed and tested against plume-rise observations. For bent-over buoyant plumes, this results in the recommendation that multiple-source rise be calculated as [(N + S)/(1 + S)]/sup 1/3/ times the single-source rise, Δh 1 , where N is the number of sources and S = 6 (total width of source configuration/N/sup 1/3/ Δh 1 )/sup 3/2/. For calm conditions a crude but simple method is suggested for predicting the height of plume merger and subsequent behavior which is based on the geometry and velocity variations of a single buoyant plume. Finally, it is suggested that large clusters of buoyant sources might occasionally give rise to concentrated vortices either within the source configuration or just downwind of it

  1. Temporal dependence of the enhancement of material removal in femtosecond-nanosecond dual-pulse laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Scaffidi, Jon; Pearman, William; Carter, J. Chance; Colston, Bill W. Jr.; Angel, S. Michael

    2004-01-01

    Despite the large neutral atomic and ionic emission enhancements that have been noted in collinear and orthogonal dual-pulse laser-induced breakdown spectroscopy, the source or sources of these significant signal and signal-to-noise ratio improvements have yet to be explained. In the research reported herein, the combination of a femtosecond preablative air spark and a nanosecond ablative pulse yields eightfold and tenfold material removal improvement for brass and aluminum, respectively, but neutral atomic emission is enhanced by only a factor of 3-4. Additionally, temporal correlation between enhancement of material removal and of atomic emission is quite poor, suggesting that the atomic-emission enhancements noted in the femtosecond-nanosecond pulse configuration result in large part from some source other than simple improvement in material removal

  2. Laser ablation comparison by picosecond pulses train and nanosecond pulse

    Science.gov (United States)

    Lednev, V. N.; Filippov, M. N.; Bunkin, A. F.; Pershin, S. M.

    2015-12-01

    A comparison of laser ablation by a train of picosecond pulses and nanosecond pulses revealed a difference in laser craters, ablation thresholds, plasma sizes and spectral line intensities. Laser ablation with a train of picosecond pulses resulted in improved crater quality while ablated mass decreased up to 30%. A reduction in laser plasma dimensions for picosecond train ablation was observed while the intensity of atomic/ionic lines in the plasma spectra was greater by a factor of 2-4 indicating an improved excitation and atomization in the plasma.

  3. Mono-energetic ions emission by nanosecond laser solid target irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Muoio, A., E-mail: Annamaria.Muoio@lns.infn.it [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Viale F.S. D’Alcontres 31, 98166 Messina (Italy); Tudisco, S. [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Altana, C. [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania (Italy); Lanzalone, G. [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Enna “Kore”, Via delle Olimpiadi, 94100 Enna (Italy); Mascali, D.; Cirrone, G.A.P.; Schillaci, F. [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Trifirò, A. [Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Viale F.S. D’Alcontres 31, 98166 Messina (Italy); Sezione INFN, Catania (Italy)

    2016-09-01

    An experimental campaign aiming to investigate the acceleration mechanisms through laser–matter interaction in nanosecond domain has been carried out at the LENS (Laser Energy for Nuclear Science) laboratory of INFN-LNS, Catania. Pure Al targets were irradiated by 6 ns laser pulses at different pumping energies, up to 2 J. Advanced diagnostics tools were used to characterize the plasma plume and ion production. We show the preliminary results of this experimental campaign, and especially the ones showing the production of multicharged ions having very narrow energy spreads.

  4. SN 2008iy: An Unusual Type IIn Supernova with an Enduring 400 Day Rise Time

    OpenAIRE

    Miller, A. A.; Silverman, J. M.; Butler, N. R.; Bloom, J. S.; Chornock, R.; Filippenko, A. V.; Ganeshalingam, M.; Klein, C. R.; Li, W.; Nugent, P. E.; Smith, N.; Steele, T. N.

    2009-01-01

    We present spectroscopic and photometric observations of the Type IIn supernova (SN) 2008iy. SN 2008iy showed an unprecedentedly long rise time of ~400 days, making it the first SN to take significantly longer than 100 days to reach peak optical luminosity. The peak absolute magnitude of SN 2008iy was M_r ~ -19.1 mag, and the total radiated energy over the first ~700 days was ~2 x 10^50 erg. Spectroscopically, SN 2008iy is very similar to the Type IIn SN 1988Z at late times, and, like SN 1988...

  5. Nanoparticle mediated ablation of breast cancer cells using a nanosecond pulsed electric field

    Science.gov (United States)

    Burford, Christopher

    In the past, both nanomaterials and various heating modalities have been researched as means for treating cancers. However, many of the current methodologies have the flaws of inconsistent tumor ablation and significant destruction of healthy cells. Based on research performed using constant radiofrequency electric fields and metallic nanoparticles (where cell necrosis is induced by the heating of these nanoparticles) we have developed a modality that simlarly uses functionalized metallic nanoparticles, specific for the T47D breast cancer cell line, and nanosecond pulsed electric fields as the hyperthermic inducer. Using both iron oxide and gold nanoparticles the results of our pilot studies indicated that up to 90% of the cancer cells were ablated given the optimal treatment parameters. These quantities of ablated cells were achieved using a cumulative exposure time 6 orders of magnitude less than most in vitro radiofrequency electric field studies.

  6. Characterization of Pressure Transients Generated by Nanosecond Electrical Pulse (nsEP) Exposure

    OpenAIRE

    Caleb C. Roth; Ronald A. Barnes Jr.; Bennett L. Ibey; Hope T. Beier; L. Christopher Mimun; Saher M. Maswadi; Mehdi Shadaram; Randolph D. Glickman

    2015-01-01

    The mechanism(s) responsible for the breakdown (nanoporation) of cell plasma membranes after nanosecond pulse (nsEP) exposure remains poorly understood. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. However, the delivery of a high-voltage nsEP to cells by tungsten electrodes creates a multitude of biophysical phenomena, including electrohydraulic cavitation, el...

  7. Nanosecond pulsed electric field suppresses development of eyes and germ cells through blocking synthesis of retinoic acid in Medaka (Oryzias latipes.

    Directory of Open Access Journals (Sweden)

    Eri Shiraishi

    Full Text Available Application of nanosecond pulsed electric fields (nsPEFs has attracted rising attention in various scientific fields including medical, pharmacological, and biological sciences, although its effects and molecular mechanisms leading to the effects remain poorly understood. Here, we show that a single, high-intensity (10-30 kV/cm, 60-ns PEF exposure affects gene expression and impairs development of eyes and germ cells in medaka (Oryzias latipes. Exposure of early blastula stage embryos to nsPEF down-regulated the expression of several transcription factors which are essential for eye development, causing abnormal eye formation. Moreover, the majority of the exposed genetic female embryos showed a fewer number of germ cells similar to that of the control (unexposed genetic male at 9 days post-fertilization (dpf. However, all-trans retinoic acid (atRA treatment following the exposure rescued proliferation of germ cells and resumption of normal eye development, suggesting that the phenotypes induced by nsPEF are caused by a decrease of retinoic acid levels. These results confirm that nsPEFs induce novel effects during embryogenesis in medaka.

  8. High pulse energy sub-nanosecond Tm-doped fiber laser

    Science.gov (United States)

    Cserteg, Andras; Guillemet, Sebastien; Hernandez, Yves; Giannone, Domenico

    2012-02-01

    We report a core pumped thulium-doped fiber amplifier that generates 1.4 μJ pulses at 1980 nm with a repetition rate of 3.6 MHz preserving the original spectral bandwidth of the oscillator. The amplifier chain is seeded by a passively modelocked fiber laser with 5 mW output power and the pulses are stretched to 800 picoseconds. The amplifier is core pumped by a single mode erbium fiber laser. The slope efficiency is 35%. To the best of our knowledge, this is the first demonstration of sub nanosecond pulses with energies higher than 1 μJ coming out of a thulium-doped fiber amplifier.

  9. Micromachining of glass by the third harmonic of nanosecond Nd:YVO{sub 4} laser

    Energy Technology Data Exchange (ETDEWEB)

    Ramil, A. [Centro de Investigacions Tecnoloxicas, Universidade da Coruna, E-15403 Ferrol (A Coruna) (Spain)], E-mail: aramil@cdf.udc.es; Lamas, J.; Alvarez, J.C.; Lopez, A.J.; Saavedra, E.; Yanez, A. [Centro de Investigacions Tecnoloxicas, Universidade da Coruna, E-15403 Ferrol (A Coruna) (Spain)

    2009-03-01

    The ablation processing of glass was performed by using the third harmonic of nanosecond Nd:YVO{sub 4} laser. The objective of this work was the formation of deep holes with a high aspect ratio in soda lime glass; with this purpose different ways to raster the glass surface with the focused laser beam, i.e., single line, parallel lines and orthogonally crossing lines, have been tried and the effect of different parameters as the number of lines and number of scans in the depth and inclination of the sidewalls of the hole has been analyzed. Moreover, to reduce the time consumption in the laser processing of glass plates the relationship between penetration depths and overlapping factor has been studied and an optimum value of scan speed has been obtained for a particular case.

  10. Nanosecond laser ablation processes in aluminum-doped zinc-oxide for photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Canteli, D., E-mail: david.canteli@ciemat.es [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Fernandez, S. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Molpeceres, C. [Centro Laser, Universidad Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain); Torres, I.; Gandia, J.J. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer A study of the ablation of AZO thin films deposited at different temperature conditions with nanosecond UV laser light for photovoltaic devices has been performed. Black-Right-Pointing-Pointer The ablation threshold of AZO thin films was measured and related with the absorption coefficient of the films at the laser wavelength, showing a direct correspondence. Black-Right-Pointing-Pointer A change in the material structure in the areas closest to the edges of laser grooves made in samples deposited at temperatures below 100 Degree-Sign C was observed and studied. - Abstract: Aiming to a future use in thin film solar modules, the processing of aluminum doped zinc oxide thin films with good optoelectronic properties with a nanosecond-pulsed ultraviolet laser has been studied. The ablation threshold fluence of the films has been determined and associated with the material properties. The ablation process has been optimized and grooves with good properties for photovoltaic devices have been obtained. The morphology of the ablated surfaces has been observed by confocal microscopy and its structure has been characterized by Raman spectroscopy. The influence of ablation parameters like focus distance, pulse energy and repetition frequency in the groove morphology has been studied with special attention to the thermal effects on the material structure.

  11. Nanosecond laser ablation processes in aluminum-doped zinc-oxide for photovoltaic devices

    International Nuclear Information System (INIS)

    Canteli, D.; Fernandez, S.; Molpeceres, C.; Torres, I.; Gandía, J.J.

    2012-01-01

    Highlights: ► A study of the ablation of AZO thin films deposited at different temperature conditions with nanosecond UV laser light for photovoltaic devices has been performed. ► The ablation threshold of AZO thin films was measured and related with the absorption coefficient of the films at the laser wavelength, showing a direct correspondence. ► A change in the material structure in the areas closest to the edges of laser grooves made in samples deposited at temperatures below 100 °C was observed and studied. - Abstract: Aiming to a future use in thin film solar modules, the processing of aluminum doped zinc oxide thin films with good optoelectronic properties with a nanosecond-pulsed ultraviolet laser has been studied. The ablation threshold fluence of the films has been determined and associated with the material properties. The ablation process has been optimized and grooves with good properties for photovoltaic devices have been obtained. The morphology of the ablated surfaces has been observed by confocal microscopy and its structure has been characterized by Raman spectroscopy. The influence of ablation parameters like focus distance, pulse energy and repetition frequency in the groove morphology has been studied with special attention to the thermal effects on the material structure.

  12. Nanosecond-pulsed Q-switched Nd:YAG laser at 1064 nm with a gold nanotriangle saturable absorber

    Science.gov (United States)

    Chen, Xiaohan; Li, Ping; Dun, Yangyang; Song, Teng; Ma, Baomin

    2018-06-01

    Gold nanotriangles (GNTs) were successfully employed as a saturable absorber (SA) to achieve passively Q-switched lasers for the first time. The performance of the Q-switched Nd:YAG laser at 1064 nm has been systematically investigated. The corresponding shortest pulsewidth, the threshold pump power and the maximum Q-switched average output power were 275.5 ns, 1.37 W, and 171 mW, respectively. To our knowledge, this is the shortest pulsewidth and the lowest threshold in a passively Q-switched laser at approximately 1.1 µm based on a gold nanoparticle SA (GNPs-SA). Our experimental results proved that the GNTs-SA can be used as a promising saturable absorber for nanosecond-pulsed lasers.

  13. Unit for the nanosecond, laser, pulse photolysis in the ultraviolet region for a combination of photochemical studies

    Energy Technology Data Exchange (ETDEWEB)

    Pikel' ni, V F; Kolosov, V A; Kiryukhin, Yu I; Kondrat' ev, V A; Borovkova, V A; Tarasov, E N

    1976-06-01

    A description is given of a nanosecond laser unit for pulse photolysis in the ultraviolet region, by means of which it is possible to investigate the kinetics of the death of interstitial particles, their optical absorption and luminescence spectra, and also the photoconductivity induced by the laser radiation, at a time resolution of about 15 ns. As a source of powerful, stable uv-radiation, use is made of the fourth harmonic (266 nm) of radiation from an aluminum-yttrium garnet containing neodymium. The radiation power of the fourth harmonic attained 2 MW. The time of bringing the unit into the operating mode is considerably shortened because of the possibility of operating in a frequency mode. Absorption spectra of carbazole in hexane were obtained at 20/sup 0/C. (SJR)

  14. Main injector synchronous timing system

    International Nuclear Information System (INIS)

    Blokland, W.; Steimel, J.

    1998-01-01

    The Synchronous Timing System is designed to provide sub-nanosecond timing to instrumentation during the acceleration of particles in the Main Injector. Increased energy of the beam particles leads to a small but significant increase in speed, reducing the time it takes to complete a full turn of the ring by 61 nanoseconds (or more than 3 rf buckets). In contrast, the reference signal, used to trigger instrumentation and transmitted over a cable, has a constant group delay. This difference leads to a phase slip during the ramp and prevents instrumentation such as dampers from properly operating without additional measures. The Synchronous Timing System corrects for this phase slip as well as signal propagation time changes due to temperature variations. A module at the LLRF system uses a 1.2 Gbit/s G-Link chip to transmit the rf clock and digital data (e.g. the current frequency) over a single mode fiber around the ring. Fiber optic couplers at service buildings split off part of this signal for a local module which reconstructs a synchronous beam reference signal. This paper describes the background, design and expected performance of the Synchronous Timing System. copyright 1998 American Institute of Physics

  15. Main injector synchronous timing system

    International Nuclear Information System (INIS)

    Blokland, Willem; Steimel, James

    1998-01-01

    The Synchronous Timing System is designed to provide sub-nanosecond timing to instrumentation during the acceleration of particles in the Main Injector. Increased energy of the beam particles leads to a small but significant increase in speed, reducing the time it takes to complete a full turn of the ring by 61 nanoseconds (or more than 3 rf buckets). In contrast, the reference signal, used to trigger instrumentation and transmitted over a cable, has a constant group delay. This difference leads to a phase slip during the ramp and prevents instrumentation such as dampers from properly operating without additional measures. The Synchronous Timing System corrects for this phase slip as well as signal propagation time changes due to temperature variations. A module at the LLRF system uses a 1.2 Gbit/s G-Link chip to transmit the rf clock and digital data (e.g. the current frequency) over a single mode fiber around the ring. Fiber optic couplers at service buildings split off part of this signal for a local module which reconstructs a synchronous beam reference signal. This paper describes the background, design and expected performance of the Synchronous Timing System

  16. A CW Gunn diode bistable switching element.

    Science.gov (United States)

    Hurtado, M.; Rosenbaum, F. J.

    1972-01-01

    Experiments with a current-controlled bistable switching element using a CW Gunn diode are reported. Switching rates of the order of 10 MHz have been obtained. Switching is initiated by current pulses of short duration (5-10 ns). Rise times of the order of several nanoseconds could be obtained.

  17. Effect of liquid gate bias rising time in pH sensors based on Si nanowire ion sensitive field effect transistors

    Science.gov (United States)

    Jang, Jungkyu; Choi, Sungju; Kim, Jungmok; Park, Tae Jung; Park, Byung-Gook; Kim, Dong Myong; Choi, Sung-Jin; Lee, Seung Min; Kim, Dae Hwan; Mo, Hyun-Sun

    2018-02-01

    In this study, we investigate the effect of rising time (TR) of liquid gate bias (VLG) on transient responses in pH sensors based on Si nanowire ion-sensitive field-effect transistors (ISFETs). As TR becomes shorter and pH values decrease, the ISFET current takes a longer time to saturate to the pH-dependent steady-state value. By correlating VLG with the internal gate-to-source voltage of the ISFET, we found that this effect occurs when the drift/diffusion of mobile ions in analytes in response to VLG is delayed. This gives us useful insight on the design of ISFET-based point-of-care circuits and systems, particularly with respect to determining an appropriate rising time for the liquid gate bias.

  18. Generation of nanosecond S band microwave pulses based on superradiance

    International Nuclear Information System (INIS)

    Ginzburg, N.S.; Zotova, I.V.; Rozental, R.M.

    2002-01-01

    Modeling carried out demonstrates possibility of generation of gigawatt power level S band microwave pulse with duration of several nanoseconds using superradiation of short electron beam moving along slow-wave periodical structure. A 10 ns / 500 keV / 5 kA accelerator of Kanazawa University can be used in such experiments. It is shown that significant increasing peak power can be obtained by optimization of voltage and current pulses waveforms. Required increasing of electron energy and current by the end of electron pulse can be achieved by using self-acceleration of a short beam passing through a system of passive cavities. (author)

  19. Generation of nanosecond S band microwave pulses based on superradiance

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, N.S.; Zotova, I.V.; Rozental, R.M. [Russian Academy of Science, Institute of Applied Physics, Nizhny Novgorod (RU)] [and others

    2002-06-01

    Modeling carried out demonstrates possibility of generation of gigawatt power level S band microwave pulse with duration of several nanoseconds using superradiation of short electron beam moving along slow-wave periodical structure. A 10 ns / 500 keV / 5 kA accelerator of Kanazawa University can be used in such experiments. It is shown that significant increasing peak power can be obtained by optimization of voltage and current pulses waveforms. Required increasing of electron energy and current by the end of electron pulse can be achieved by using self-acceleration of a short beam passing through a system of passive cavities. (author)

  20. Modelling of heating and photoexcitation of single-crystal silicon under multipulse irradiation by a nanosecond laser at 1.06 μm

    Science.gov (United States)

    Polyakov, D. S.; Yakovlev, E. B.

    2018-03-01

    We report a theoretical study of heating and photoexcitation of single-crystal silicon by nanosecond laser radiation at a wavelength of 1.06 μm. The proposed physicomathematical model of heating takes into account the complex nonlinear dynamics of the interband absorption coefficient of silicon and the contribution of the radial heat removal to the cooling of silicon between pulses under multipulse irradiation, which allows one to obtain a satisfactory agreement between theoretical predictions of silicon melting thresholds at different nanosecond pulse durations and experimental data (both under single-pulse and multipulse irradiation). It is found that under irradiation by nanosecond pulses at a wavelength of 1.06 μm, the dynamic Burshtein–Moss effect can play an important role in processes of photoexcitation and heating. It is shown that with the regimes typical for laser multipulse microprocessing of silicon (the laser spot diameter is less than 100 μm, and the repetition rate of pulses is about 100 kHz), the radial heat removal cannot be neglected in the analysis of heat accumulation processes.

  1. Explosive Processes on Cathode while Forming Nanosecond Pulsed Discharge of High Pressure

    Directory of Open Access Journals (Sweden)

    A. M. Hashimov

    2012-01-01

    Full Text Available The paper is devoted to research of cathode surfaces with different curvature radius (r = 1–8 mm while forming nanosecond pulsed discharge in dense air. Influence of field and air pressure heterogeneity rate in gas gap on size of micro-craters being formed on working cathode surface after pulsed effect has been shown in the paper. The paper reveals a maximum expansion of separate micro-crater size on cathode surface with small curvature radius.

  2. One magnet module of the full-aperture kicker

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    Nine such modules, in a single vacuum tank, form the complete kicker. Ferrite rings (not visible), in conjunction with the capacitance between the plates, create the electrical equivalent of a transmission line. A fast 40 kV pulse is applied, and field rise times of 70-80 nanoseconds can be obtained.

  3. Study on the characteristics of barrier free surface discharge driven by repetitive nanosecond pulses at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Pang; Qiaogen, Zhang [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Kun, He [China Electric Power Research Institute, Beijing 100192 (China); Chunliang, Liu [State Key Laboratory for Physical Electronics and Devices, Xi' an Jiaotong University, Xi' an 710049 (China)

    2016-05-15

    Nanosecond pulsed plasma has an enormous potential in many applications. In this paper, the characteristics of barrier free nanosecond pulsed surface discharge are investigated by the use of an actuator with a strip-strip film electrode configuration, including the effect of electrode width and the gap distance on the plasma morphology and electrical characteristics at atmospheric pressure. It was found that it is relative easier to generate a quasi uniform discharge with a thinner electrode width and a smaller gap distance. The underlying physical mechanism was also discussed. Besides that, the influence of airflow on repetitive pulsed surface discharge was examined. By comparing to the discharge produced by two different pulse waveforms in airflows, we found that the discharge driven by a faster pulse behaves more stable. Finally, a model was developed to analyze the interaction of the airflow and the discharge channels.

  4. A 350 KV nanosecond pulse voltage generator with adjustable pulsed-width

    International Nuclear Information System (INIS)

    Wang, X.; Wang, M.; Chen, Y.Q.; Zeng, L.G.; Han, M.

    2002-01-01

    This paper presents a 350 kV nanosecond pulse voltage generator (NPVG). The voltage pulsed-width can be adjusted from 30 to 160 ns. The generator consists of: Marx generator, pulsed forming line (PFL), main switch and matched impedance. The output voltage of Marx generator is over than nU c (n- the stage number of Marx generator, U c -the charging voltage of capacitor). When the pulse forming line is terminated with an impedance that is over than the characteristic impedance of PFL, the higher voltage pulse was provided for the load

  5. Low-Cost Facile Fabrication of Flexible Transparent Copper Electrodes by Nanosecond Laser Ablation

    KAUST Repository

    Paeng, Dongwoo

    2015-03-27

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Low-cost Cu flexible transparent conducting electrodes (FTCEs) are fabricated by facile nanosecond laser ablation. The fabricated Cu FTCEs show excellent opto-electrical properties (transmittance: 83%, sheet resistance: 17.48 Ω sq-1) with outstanding mechanical durability. Successful demonstration of a touch-screen panel confirms the potential applicability of Cu FTCEs to the flexible optoelectronic devices.

  6. Efficient temporal compression of coherent nanosecond pulses in compact SBS generator-amplifier setup

    OpenAIRE

    Schiemann, S.; Ubachs, W.M.G.; Hogervorst, W.

    1997-01-01

    A pulse compressor based on stimulated Brillouin scattering (SBS) in liquids is experimentally and theoretically investigated. It allows for the compression of Fourier-transform limited nanosecond pulses of several hundreds of millijoules of energy with both high conversion efficiency and a high temporal compression factor. The two-cell generator-amplifier arrangement is of a compact design not requiring external attenuation of the generator cell input energy. Pulses from an injection-seeded,...

  7. Rapid formation of electric field profiles in repetitively pulsed high-voltage high-pressure nanosecond discharges

    International Nuclear Information System (INIS)

    Ito, Tsuyohito; Kobayashi, Kazunobu; Hamaguchi, Satoshi; Czarnetzki, Uwe

    2010-01-01

    Rapid formation of electric field profiles has been observed directly for the first time in nanosecond narrow-gap parallel-plate discharges at near-atmospheric pressure. The plasmas examined here are of hydrogen, and the field measurement is based on coherent Raman scattering (CRS) by hydrogen molecules. Combined with the observation of spatio-temporal light emission profiles by a high speed camera, it has been found that the rapid formation of a high-voltage thin cathode sheath is accompanied by fast propagation of an ionization front from a region near the anode. Unlike well-known parallel-plate discharges at low pressure, the discharge formation process at high pressure is almost entirely driven by electron dynamics as ions and neutral species are nearly immobile during the rapid process. (fast track communication)

  8. Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

    Science.gov (United States)

    Besozzi, E.; Maffini, A.; Dellasega, D.; Russo, V.; Facibeni, A.; Pazzaglia, A.; Beghi, M. G.; Passoni, M.

    2018-03-01

    In this work, we exploit nanosecond laser irradiation as a compact solution for investigating the thermomechanical behavior of tungsten materials under extreme thermal loads at the laboratory scale. Heat flux factor thresholds for various thermal effects, such as melting, cracking and recrystallization, are determined under both single and multishot experiments. The use of nanosecond lasers for mimicking thermal effects induced on W by fusion-relevant thermal loads is thus validated by direct comparison of the thresholds obtained in this work and the ones reported in the literature for electron beams and millisecond laser irradiation. Numerical simulations of temperature and thermal stress performed on a 2D thermomechanical code are used to predict the heat flux factor thresholds of the different thermal effects. We also investigate the thermal effect thresholds of various nanostructured W coatings. These coatings are produced by pulsed laser deposition, mimicking W coatings in tokamaks and W redeposited layers. All the coatings show lower damage thresholds with respect to bulk W. In general, thresholds decrease as the porosity degree of the materials increases. We thus propose a model to predict these thresholds for coatings with various morphologies, simply based on their porosity degree, which can be directly estimated by measuring the variation of the coating mass density with respect to that of the bulk.

  9. System-Level Demonstration of a Dynamically Reconfigured Burst-Mode Link Using a Nanosecond Si-Photonic Switch

    DEFF Research Database (Denmark)

    Forencich, Alex; Kamchevska, Valerija; Dupuis, Nicolas

    2018-01-01

    Using a novel FPGA-based network emulator, microsecond-scale packets with 12.5-20-Gb/s data are generated, routed through a nanosecond Si-photonic switch, and received in a fast-locking burst-mode receiver. Error-free links with <382-ns system-level switching are shown....

  10. High optical label switching add-drop multiplexer nodes with nanoseconds latency for 5G metro/access networks

    NARCIS (Netherlands)

    Calabretta, N.; Miao, W.; De Waardt, H.

    2016-01-01

    We present a novel optical add-drop multiplexer for next-generation metro/access networks by exploiting optical label switching technology. Experimental results of a ring network show nanoseconds add/drop operation including multicasting and power equalization of 50Gb/s data.

  11. Texturing of polypropylene (PP) with nanosecond lasers

    Science.gov (United States)

    Riveiro, A.; Soto, R.; del Val, J.; Comesaña, R.; Boutinguiza, M.; Quintero, F.; Lusquiños, F.; Pou, J.

    2016-06-01

    Polypropylene (PP) is a biocompatible and biostable polymer, showing good mechanical properties that has been recently introduced in the biomedical field for bone repairing applications; however, its poor surface properties due to its low surface energy limit their use in biomedical applications. In this work, we have studied the topographical modification of polypropylene (PP) laser textured with Nd:YVO4 nanosecond lasers emitting at λ = 1064 nm, 532 nm, and 355 nm. First, optical response of this material under these laser wavelengths was determined. The application of an absorbing coating was also studied. The influence of the laser processing parameters on the surface modification of PP was investigated by means of statistically designed experiments. Processing maps to tailor the roughness, and wettability, the main parameters affecting cell adhesion characteristics of implants, were also determined. Microhardness measurements were performed to discern the impact of laser treatment on the final mechanical properties of PP.

  12. Time characteristics of a self quenching streamer in the coexistence region

    International Nuclear Information System (INIS)

    Han Jiaxiang; Li Cheng; Xu Zizong; Chen Honfang

    1994-01-01

    Experimental studies on the time correlation between electrical signals in the primary avalanche and optical signals which are emitted in the avalanches of the limited proportional mode and the self quenching streamer (SQS) mode have demonstrated that there exists a weak optical emission which is almost simultaneous with the limited proportional avalanche, that a streamer pulse in the SQS mode has a few nanoseconds delay relative to the primary avalanche, and that the spread of the delay (FWHM) is also a few nanoseconds. ((orig.))

  13. Micro-processing of NiMnGa shape memory alloy by using a nanosecond fiber laser

    Science.gov (United States)

    Biffi, C. A.; Tuissi, A.

    2016-04-01

    The interest on Ferromagnetic Shape Memory Alloys (FSMAs), such as NiMnGa, is growing up, thanks to their functional properties to be employed in a new class of micro-devices. The most evident critical issue, limiting the use of these systems in the production of industrial devices, is the brittleness of the bulk material; its workability by using convectional processing methods is very limited. Thus, alternative processing methods, including laser processing, are encouraged for the manufacture of FSMAs based new devices. In this work, the effect of the nanosecond laser microprocessing on Ni45Mn33Ga22 [at%] has been studied. Linear grooves were realized by a nanosecond 30 W fiber laser; the machined surfaces were analyzed with scanning electron microscopy, coupled with energetic dispersion spectroscopy for the composition analysis. The morphology of the grooves was affected by the laser scanning velocity and the number of laser pulses while the measured material removal rate appeared to be influenced mainly by the number of laser pulses. Compositional modification, associated to the loss of Ga content, was detected only for the lower scanning velocity, because of the high fluence. On the contrary, by increasing the velocity up to 1000 mm/s no Ga loss can be seen, making possible the laser processing of this functional alloy without its chemical modification. The use of short pulses allowed also to reduce the amount of recast material and the compositional change with respect to long pulses. Finally, the calorimetric analysis indicated that laser nanosecond microprocessing could affect the functional properties of this alloy: a larger decrease of the characteristic temperatures of the martensitic transformation was observed in correspondence of the low scanning velocity.

  14. Nanosecond laser texturing of uniformly and non-uniformly wettable micro structured metal surfaces for enhanced boiling heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Zupančič, Matevž, E-mail: matevz.zupancic@fs.uni-lj.si; Može, Matic; Gregorčič, Peter; Golobič, Iztok

    2017-03-31

    Highlights: • Surfaces with periodically changed wettability were produced by a ns marking laser. • Heat transfer was investigated on uniformly and non-uniformly wettable surfaces. • Microporous surfaces with non-uniform wettability enhance boiling heat transfer. • The most bubble nucleations were observed in the vicinity of the microcavities. • Results agree with the predictions of the nucleation criteria. - Abstract: Microstructured uniformly and non-uniformly wettable surfaces were created on 25-μm-thin stainless steel foils by laser texturing using a marking nanosecond Nd:YAG laser (λ = 1064 nm) and utilizing various laser fluences and scan line separations. High-speed photography and high-speed IR thermography were used to investigate nucleate boiling heat transfer on the microstructured surfaces. The most pronounced results were obtained on a surface with non-uniform microstructure and non-uniform wettability. The obtained results show up to a 110% higher heat transfer coefficients and 20–40 times higher nucleation site densities compared to the untextured surface. We show that the number of active nucleation sites is significantly increased in the vicinity of microcavities that appeared in areas with the smallest (10 μm) scan line separation. Furthermore, this confirms the predictions of nucleation criteria and proves that straightforward, cost-effective nanosecond laser texturing allows the production of cavities with diameters of up to a few micrometers and surfaces with non-uniform wettability. Additionally, this opens up important possibilities for a more deterministic control over the complex boiling process.

  15. Laser ablation of lysozyme with UV, visible and infrared femto- and nanosecond pulses

    DEFF Research Database (Denmark)

    Schou, Jørgen; Canulescu, Stela; Matei, Andreea

    Lysozyme is an interesting molecule for laser ablation of organic materials, because the ablation has been comprehensively studied, it is a medium heavy molecule with a mass of 14305 Da, which can be detected by standard techniques, and because it is used as a bactericidal protein in the food...... industry. Lysozyme molecules do not absorb energy for wavelengths above 310 nm, but nevertheless there is a strong mass loss by ablation for laser irradiation in the visible regime. The total ablation yield of lysozyme at 355 nm and at 2 J/cm2 is about 155 µg/pulse, possibly one of the highest ablation...... the ablation process for different wavelengths and time duration. Measurements for 6-7-ns laser ablation were carried out at DTU on Risø Campus, while measurements with pulses of 300 fs were carried out at the University of Naples in a similar setup. For all wavelengths except at nanosecond laser pulses at 355...

  16. Comparative study of femtosecond and nanosecond laser-induced breakdown spectroscopy of depleted uranium

    International Nuclear Information System (INIS)

    Emmert, Luke A.; Chinni, Rosemarie C.; Cremers, David A.; Jones, C. Randy; Rudolph, Wolfgang

    2011-01-01

    We present spectra of depleted uranium metal from laser plasmas generated by nanosecond Nd:YAG (1064 nm) and femtosecond Ti:sapphire (800 nm) laser pulses. The latter pulses produce short-lived and relatively cool plasmas in comparison to the longer pulses, and the spectra of neutral uranium atoms appear immediately after excitation. Evidence for nonequilibrium excitation with femtosecond pulses is found in the dependence of spectral line intensities on the pulse chirp.

  17. Studies of multi-wavelength laser-induced damage on KDP crystals in the nanosecond regime

    International Nuclear Information System (INIS)

    Reyne, Stephane

    2011-01-01

    This thesis interests in the laser-induced damage mechanisms of KDP and DKDP crystals in the nanosecond regime. KDP is a non-linear material particularly used in the frequency converters of the Laser MegaJoule, which is under construction at the CEA-Cesta in France. For this facility, the KDP laser damage resistance is one of the keystones and is still under investigations to fix this problem. This is why this manuscript presents different studies which highlight the two main aspects of the nanosecond laser-induced damage of KDP frequency converters: the precursor defects and the mechanisms to initiate damage. First, we propose a study based on the analysis of several photos obtained by DIC microscopy of damage initiated by different wavelengths. A comparison with a code coupling the energy deposition and hydrodynamic is also done. Then, we interest in the influence of the defects geometry through a study based on the laser polarization effect on the laser damage resistance. By the comparison with a CEA home-made code, this study particularly underlines the possibility to define a new geometry for the precursor defects. This geometry proposed has the shape of an ellipsoid and is supposed to keep the crystal structure properties. Finally, we enlarge on the physical mechanisms initiating laser damage with pump-pump experiments. These tests consist in combining two radiations of different wavelengths which impacting the crystal simultaneously or are delayed one by the other. We then observe the influence of this wavelengths mixing on the KDP laser damage resistance. In particular, a coupling effect between the wavelengths of the mixture may occur as a function of the fluences combination. Finally, the goal of these specific studies is to accumulate new data in order to improve the understanding in the initiation of the laser damage in KDP and DKDP crystals in the nanosecond regime. In the end, these data will allow us to develop predictive models to simulate the laser

  18. Note: Tesla based pulse generator for electrical breakdown study of liquid dielectrics

    Science.gov (United States)

    Veda Prakash, G.; Kumar, R.; Patel, J.; Saurabh, K.; Shyam, A.

    2013-12-01

    In the process of studying charge holding capability and delay time for breakdown in liquids under nanosecond (ns) time scales, a Tesla based pulse generator has been developed. Pulse generator is a combination of Tesla transformer, pulse forming line, a fast closing switch, and test chamber. Use of Tesla transformer over conventional Marx generators makes the pulse generator very compact, cost effective, and requires less maintenance. The system has been designed and developed to deliver maximum output voltage of 300 kV and rise time of the order of tens of nanoseconds. The paper deals with the system design parameters, breakdown test procedure, and various experimental results. To validate the pulse generator performance, experimental results have been compared with PSPICE simulation software and are in good agreement with simulation results.

  19. Minimization of the external heating power by long fusion power rise-up time for self-ignition access in the helical reactor FFHR2m

    International Nuclear Information System (INIS)

    Mitarai, O.; Sagara, A.; Chikaraishi, H.; Imagawa, S.; Shishkin, A.A.; Motojima, O.

    2006-10-01

    Minimization of the external heating power to access self-ignition is advantageous to increase the reactor design flexibility and to reduce the capital and operating costs of the plasma heating device in a helical reactor. In this work we have discovered that a larger density limit leads to a smaller value of the required confinement enhancement factor, lower density limit margin reduces the external heating power, and over 300 s of the fusion power rise-up time makes it possible to reach a minimized heating power. While the fusion power rise-up time in a tokamak is limited by the OH transformer flux or the current drive capability, any fusion power rise-up time can be employed in a helical reactor for reducing the thermal stresses of the blanket and shields, because the confinement field is generated by the external helical coils. (author)

  20. Characteristics of a novel nanosecond DBD microplasma reactor for flow applications

    Science.gov (United States)

    Elkholy, A.; Nijdam, S.; van Veldhuizen, E.; Dam, N.; van Oijen, J.; Ebert, U.; de Goey, L. Philip H.

    2018-05-01

    We present a novel microplasma flow reactor using a dielectric barrier discharge (DBD) driven by repetitive nanosecond high-voltage pulses. Our DBD-based geometry can generate a non-thermal plasma discharge at atmospheric pressure and below in a regular pattern of micro-channels. This reactor can work continuously up to about 100 min in air, depending on the pulse repetition rate and operating pressure. We here present the geometry and main characteristics of the reactor. Pulse energies of 1.46 and 1.3 μJ per channel at atmospheric pressure and 50 mbar, respectively, have been determined by time-resolved measurements of current and voltage. Time-resolved optical emission spectroscopy measurements have been performed to calculate the relative species concentrations and temperatures (vibrational and rotational) of the discharge. The effects of the operating pressure and flow velocity on the discharge intensity have been investigated. In addition, the effective reduced electric field strength {(E/N)}eff} has been obtained from the intensity ratio of vibronic emission bands of molecular nitrogen at different operating pressures and different locations. The derived {(E/N)}eff} increases gradually from about 550 to 4600 Td when decreasing the pressure from 1 bar to 100 mbar. Below 100 mbar, further pressure reduction results in a significant increase in {(E/N)}eff} up to about 10000 Td at 50 mbar.

  1. Nanosecond high-voltage generators for supplying the kickers of charged particle accelerators

    International Nuclear Information System (INIS)

    Korchuganov, V.N.; Matveev, Yu.G.; Shvedov, D.A.

    2000-01-01

    The high-voltage nanosecond generators (VNG) of rectangular pulses, developed for supplying the injection and extraction kickers of the accelerator-storage complexes are considered in this work. The pulse hydrogen thyratrons and gas-filled discharges are used as commutators in those generators. If necessary, the VNG pulses fronts may be shortened up to 2-3 ns in the coaxial lines, filled with ferrite rings. The mechanism of the pulse fronts shortening was considered earlier. The basis parameters of the VNG various types are presented [ru

  2. Numerical investigation of heating of a gold nanoparticle and the surrounding microenvironment by nanosecond laser pulses for nanomedicine applications

    International Nuclear Information System (INIS)

    Sassaroli, E; Li, K C P; O'Neill, B E

    2009-01-01

    We have modeled, by finite element analysis, the process of heating of a spherical gold nanoparticle by nanosecond laser pulses and of heat transfer between the particle and the surrounding medium, with no mass transfer. In our analysis, we have included thermal conductivity changes, vapor formation, and changes of the dielectric properties as a function of temperature. We have shown that such changes significantly affect the temperature reached by the particle and surrounding microenvironment and therefore the thermal and dielectric properties of the medium need to be known for a correct determination of the temperature elevation. We have shown that for sufficiently low intensity and long pulses, it is possible to establish a quasi-steady temperature profile in the medium with no vapor formation. As the intensity is increased, a phase-change with vapor formation takes place around the gold nanoparticle. As phase-transition starts, an additional increase in the intensity does not significantly increase the temperature of the gold nanoparticle and surrounding environment. The temperature starts to rise again above a given intensity threshold which is particle and environment dependent. The aim of this study is to provide useful insights for the development of molecular targeting of gold nanoparticles for applications such as remote drug release of therapeutics and photothermal cancer therapy.

  3. Numerical investigation of heating of a gold nanoparticle and the surrounding microenvironment by nanosecond laser pulses for nanomedicine applications

    Energy Technology Data Exchange (ETDEWEB)

    Sassaroli, E; Li, K C P; O' Neill, B E [Department of Radiology, Methodist Hospital Research Institute, Houston, TX, 77030 (United States)], E-mail: beoneill@tmhs.org

    2009-09-21

    We have modeled, by finite element analysis, the process of heating of a spherical gold nanoparticle by nanosecond laser pulses and of heat transfer between the particle and the surrounding medium, with no mass transfer. In our analysis, we have included thermal conductivity changes, vapor formation, and changes of the dielectric properties as a function of temperature. We have shown that such changes significantly affect the temperature reached by the particle and surrounding microenvironment and therefore the thermal and dielectric properties of the medium need to be known for a correct determination of the temperature elevation. We have shown that for sufficiently low intensity and long pulses, it is possible to establish a quasi-steady temperature profile in the medium with no vapor formation. As the intensity is increased, a phase-change with vapor formation takes place around the gold nanoparticle. As phase-transition starts, an additional increase in the intensity does not significantly increase the temperature of the gold nanoparticle and surrounding environment. The temperature starts to rise again above a given intensity threshold which is particle and environment dependent. The aim of this study is to provide useful insights for the development of molecular targeting of gold nanoparticles for applications such as remote drug release of therapeutics and photothermal cancer therapy.

  4. Universal pulse generator with a nanosecond fast responce

    International Nuclear Information System (INIS)

    Basiladze, S.G.; Nguen Kuang Min'.

    1977-01-01

    A pulse generator with nanosecond action is described; it is mainly designed for testing and tuning fast electronic devices operating with pulses in the N/1/M standard. The generator is principally based on integral circuits and has wide functional potentialities: it includes a main-pulse channel, a delayed-pulse channel, and an overall output, which sums up these pulses; in addition to the logic pulse outputs it includes a linear pulse output with an amplitude smoothly regulated in the range from 0.3 to 6.0 V; it can operate in the self-oscillation mode, in the pulse series formation mode, in the starting mode, and in the single-start mode. Two generators are placed in a double-width CAMAC cell. The generation frequency is from 3 Hz to 75 MHz, pulse duration from 8 to 320 ns, and pulse front duration 2 ns

  5. A comparison between spectra of runaway electron beams in SF6 and air

    International Nuclear Information System (INIS)

    Zhang, Cheng; Wang, Ruexue; Yan, Ping; Shao, Tao; Tarasenko, Victor; Gu, Jianwei; Baksht, Evgenii

    2015-01-01

    Runaway electron (RAE) with extremely high-energy plays important role on the avalanche propagation, streamer formation, and ionization waves in nanosecond-pulse discharges. In this paper, the generation of a supershort avalanche electron beam (SAEB) in SF 6 and air in an inhomogeneous electric field is investigated. A VPG-30-200 generator with a pulse rise time of ∼1.6 ns and a full width at half maximum of 3–5 ns is used to produce RAE beams. The SAEBs in SF 6 and air are measured by using aluminum foils with different thicknesses. Furthermore, the SAEB spectra in SF 6 and air at pressures of 7.5 Torr, 75 Torr, and 750 Torr are compared. The results showed that amplitude of RAE beam current generated at the breakdown in SF 6 was approximately an order of magnitude less than that in air. The energy of SAEB in air was not smaller than that in SF 6 in nanosecond-pulse discharges under otherwise equal conditions. Moreover, the difference between the maximum energy of the electron distributions in air and SF 6 decreased when the rise time of the voltage pulse increased. It was because the difference between the breakdown voltages in air and SF 6 decreased when the rise time of the voltage pulse increased

  6. Supershort avalanche electron beam in SF6 and krypton

    Science.gov (United States)

    Zhang, Cheng; Tarasenko, Victor F.; Gu, Jianwei; Baksht, Evgeni Kh.; Beloplotov, Dmitry V.; Burachenko, Alexander G.; Yan, Ping; Lomaev, Mikhail I.; Shao, Tao

    2016-03-01

    Runaway electrons play an important role in the avalanche formation in nanosecond- and subnanosecond- pulse discharges. In this paper, characteristics of a supershort avalanche electron beam (SAEB) generated at the subnanosecond and nanosecond breakdown in sulfur hexafluoride (SF6 ) in an inhomogeneous electric field were studied. One pulser operated at negative polarity with voltage pulse amplitude of ˜130 kV and rise time of 0.3 ns. The other pulser operated at negative polarity with voltage pulse amplitude of 70 kV and rise time of ˜1.6 ns . SAEB parameters in SF6 are compared with those obtained in krypton (Kr), nitrogen (N2 ), air, and mixtures of SF6 with krypton or nitrogen. Experimental results showed that SAEB currents appeared during the rise-time of the voltage pulse for both pulsers. Moreover, amplitudes of the SAEB current in SF6 and Kr approximately ranged from several to tens of milliamps at atmospheric pressure, which were smaller than those in N2 and air (ranging from hundreds of milliamps to several amperes). Furthermore, the concentration of SF6 additive could significantly reduce the SAEB current in N2-SF6 mixture, but it slightly affected the SAEB current in Kr -SF6 mixture because of the atomic/molecular ionization cross section of the gas had a much greater impact on the SAEB current rather than the electronegativity.

  7. A comparison between spectra of runaway electron beams in SF6 and air

    Science.gov (United States)

    Zhang, Cheng; Tarasenko, Victor; Gu, Jianwei; Baksht, Evgenii; Wang, Ruexue; Yan, Ping; Shao, Tao

    2015-12-01

    Runaway electron (RAE) with extremely high-energy plays important role on the avalanche propagation, streamer formation, and ionization waves in nanosecond-pulse discharges. In this paper, the generation of a supershort avalanche electron beam (SAEB) in SF6 and air in an inhomogeneous electric field is investigated. A VPG-30-200 generator with a pulse rise time of ˜1.6 ns and a full width at half maximum of 3-5 ns is used to produce RAE beams. The SAEBs in SF6 and air are measured by using aluminum foils with different thicknesses. Furthermore, the SAEB spectra in SF6 and air at pressures of 7.5 Torr, 75 Torr, and 750 Torr are compared. The results showed that amplitude of RAE beam current generated at the breakdown in SF6 was approximately an order of magnitude less than that in air. The energy of SAEB in air was not smaller than that in SF6 in nanosecond-pulse discharges under otherwise equal conditions. Moreover, the difference between the maximum energy of the electron distributions in air and SF6 decreased when the rise time of the voltage pulse increased. It was because the difference between the breakdown voltages in air and SF6 decreased when the rise time of the voltage pulse increased.

  8. A comparison between spectra of runaway electron beams in SF{sub 6} and air

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Cheng; Wang, Ruexue; Yan, Ping; Shao, Tao, E-mail: st@mail.iee.ac.cn [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Tarasenko, Victor [Institute of High Current Electronics, 2/3 Akademichesky Ave., Tomsk 634055 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk 634050 (Russian Federation); Gu, Jianwei [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Baksht, Evgenii [Institute of High Current Electronics, 2/3 Akademichesky Ave., Tomsk 634055 (Russian Federation)

    2015-12-15

    Runaway electron (RAE) with extremely high-energy plays important role on the avalanche propagation, streamer formation, and ionization waves in nanosecond-pulse discharges. In this paper, the generation of a supershort avalanche electron beam (SAEB) in SF{sub 6} and air in an inhomogeneous electric field is investigated. A VPG-30-200 generator with a pulse rise time of ∼1.6 ns and a full width at half maximum of 3–5 ns is used to produce RAE beams. The SAEBs in SF{sub 6} and air are measured by using aluminum foils with different thicknesses. Furthermore, the SAEB spectra in SF{sub 6} and air at pressures of 7.5 Torr, 75 Torr, and 750 Torr are compared. The results showed that amplitude of RAE beam current generated at the breakdown in SF{sub 6} was approximately an order of magnitude less than that in air. The energy of SAEB in air was not smaller than that in SF{sub 6} in nanosecond-pulse discharges under otherwise equal conditions. Moreover, the difference between the maximum energy of the electron distributions in air and SF{sub 6} decreased when the rise time of the voltage pulse increased. It was because the difference between the breakdown voltages in air and SF{sub 6} decreased when the rise time of the voltage pulse increased.

  9. Comparison of treatment with an Alexandrite picosecond laser and Nd:YAG nanosecond laser for removing blue-black Chinese eyeliner tattoos.

    Science.gov (United States)

    Zhang, Mengli; Huang, Yuqing; Lin, Tong; Wu, Qiuju

    2018-02-28

    To retrospectively evaluate the efficacy of an Alexandrite picosecond laser versus Nd:YAG nanosecond laser for removing blue-black eyeliner tattoos which have existed more than 10 years. A total of 40 patients were treated with an Alexandrite picosecond laser in our department from August 2015 to July 2017, with a fluence of 1.96-6.37J/cm 2 , spot size of 2.0-3.6 mm, and pulse width of 750 ps. Another 32 patients were treated with an Nd:YAG nanosecond laser, with a fluence of 2.80-7.00 J/cm 2 , spot size of 3 mm, and pulse width of 5-20 ns. All analysed patients completed at least one treatment and follow-up. The median number of treatment for all the patients was 1 (range, 1-4). After a single session, no difference was found between the two lasers for the eyeliner removal (p > 0.05). For the people who achieved an excellent response of tattoo clearance, there was still no difference between the two groups (p > 0.05). Transient side effects were observed in two groups, but neither group had significant adverse reactions. To treat blue-black Chinese eyeliner tattoos over 10 years, Alexandrite picosecond laser does not provide better clearance than the Nd:YAG nanosecond laser.

  10. Synthesis of polycaprolactone-titanium oxide multilayer films by nanosecond laser pulses and electrospinning technique for better implant fabrication

    Science.gov (United States)

    Naghshine, Babak B.; Cosman, James A.; Kiani, Amirkianoosh

    2016-08-01

    In this study, a combination of electrospinning and laser texturing is introduced as a novel method for increasing the biocompatibility of metal implants. Besides having a rough laser treated surface, the implant benefits from the high porosity and better wettability of an electrospun fibrous structure, which is a more favorable environment for cell proliferation. Titanium samples were patterned using a nanosecond laser beam and were placed as collectors in an electrospinning machine. They were then soaked in simulated body fluid for four weeks. Energy Dispersive X-ray and X-Ray Diffraction results indicate significantly more hydroxyapatite formation on laser treated samples with nanoscale fibers deposited on their surface. This shows that having a laser treated surface underneath the fibrous layer can improve short-term biocompatibility even before degradation of fibers. The thermal conductivity of the electrospun layer, measured using a Hot Disk Transient Plane Source instrument and computer code, was shown to be considerably lower than that of titanium and very close to bone. The presence of this layer can therefore be beneficial in making the implant more compatible to a biological medium. In case of dental implants, it was shown that this layer can act as a thermal barrier while a hot beverage is consumed and it can decrease the temperature rise by about 60%, which avoids any possible damage to newly formed cells during the healing period.

  11. Synthesis of polycaprolactone-titanium oxide multilayer films by nanosecond laser pulses and electrospinning technique for better implant fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Naghshine, Babak B.; Cosman, James A.; Kiani, Amirkianoosh, E-mail: a.kiani@unb.ca [Silicon Hall: Laser Micro/Nano Fabrication Laboratory, Department of Mechanical Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3 (Canada)

    2016-08-28

    In this study, a combination of electrospinning and laser texturing is introduced as a novel method for increasing the biocompatibility of metal implants. Besides having a rough laser treated surface, the implant benefits from the high porosity and better wettability of an electrospun fibrous structure, which is a more favorable environment for cell proliferation. Titanium samples were patterned using a nanosecond laser beam and were placed as collectors in an electrospinning machine. They were then soaked in simulated body fluid for four weeks. Energy Dispersive X-ray and X-Ray Diffraction results indicate significantly more hydroxyapatite formation on laser treated samples with nanoscale fibers deposited on their surface. This shows that having a laser treated surface underneath the fibrous layer can improve short-term biocompatibility even before degradation of fibers. The thermal conductivity of the electrospun layer, measured using a Hot Disk Transient Plane Source instrument and computer code, was shown to be considerably lower than that of titanium and very close to bone. The presence of this layer can therefore be beneficial in making the implant more compatible to a biological medium. In case of dental implants, it was shown that this layer can act as a thermal barrier while a hot beverage is consumed and it can decrease the temperature rise by about 60%, which avoids any possible damage to newly formed cells during the healing period.

  12. Kickers and power supplies for the Fermilab Tevatron I antiproton source

    International Nuclear Information System (INIS)

    Castellano, T.; Bartoszek, L.; Tilles, E.; Petter, J.; McCarthy, J.

    1985-05-01

    The Fermilab Antiproton Source Accumulator and Debuncher rings require 5 kickers in total. These range in design from conventional ferrite delay line type magnets, with ceramic beam tubes to mechanically complex shuttered kickers situated entirely in the Accumulator Ring's 10 -10 torr vacuum. Power supplies are thyratron switched pulse forming networks that produce microsecond width pulses of several kiloamps with less than 30 nanoseconds rise and fall times. Kicker and power supply design requirements for field strength, vacuum, rise and fall time, timing and magnetic shielding of the stacked beam in the accumulator by the eddy current shutter will be discussed. 8 refs., 3 figs., 2 tabs

  13. Strategic advantages of high-rise construction

    Directory of Open Access Journals (Sweden)

    Yaskova Natalya

    2018-01-01

    Full Text Available Traditional methods to assess the competitiveness of different types of real estate in the context of huge changes of new technological way of life don’t provide building solutions that would be correct from a strategic perspective. There are many challenges due to changes in the consumers’ behavior in the housing area. A multiplicity of life models, a variety of opportunities and priorities, traditions and new trends in construction should be assessed in terms of prospective benefits in the environment of the emerging new world order. At the same time, the mane discourse of high-rise construction mainly relates to its design features, technical innovations, and architectural accents. We need to clarify the criteria for economic evaluation of high-rise construction in order to provide decisions with clear and quantifiable contexts. The suggested approach to assessing the strategic advantage of high-rise construction and the prospects for capitalization of high-rise buildings poses new challenges for the economy to identify adequate quantitative assessment methods of the high-rise buildings economic efficiency, taking into account all stages of their life cycle.

  14. Strategic advantages of high-rise construction

    Science.gov (United States)

    Yaskova, Natalya

    2018-03-01

    Traditional methods to assess the competitiveness of different types of real estate in the context of huge changes of new technological way of life don't provide building solutions that would be correct from a strategic perspective. There are many challenges due to changes in the consumers' behavior in the housing area. A multiplicity of life models, a variety of opportunities and priorities, traditions and new trends in construction should be assessed in terms of prospective benefits in the environment of the emerging new world order. At the same time, the mane discourse of high-rise construction mainly relates to its design features, technical innovations, and architectural accents. We need to clarify the criteria for economic evaluation of high-rise construction in order to provide decisions with clear and quantifiable contexts. The suggested approach to assessing the strategic advantage of high-rise construction and the prospects for capitalization of high-rise buildings poses new challenges for the economy to identify adequate quantitative assessment methods of the high-rise buildings economic efficiency, taking into account all stages of their life cycle.

  15. Widely-duration-tunable nanosecond pulse Nd:YVO4 laser based on double Pockels cells

    Science.gov (United States)

    He, Li-Jiao; Liu, Ke; Bo, Yong; Wang, Xiao-Jun; Yang, Jing; Liu, Zhao; Zong, Qing-Shuang; Peng, Qin-Jun; Cui, Da-Fu; Xu, Zu-Yan

    2018-05-01

    The development of duration-tunable pulse lasers with constant output power is important for scientific research and materials processing. We present a widely-duration-tunable nanosecond (ns) pulse Nd:YVO4 laser based on double Pockels cells (PCs), i.e. inserting an extra PC into a conventional electro-optic Q-switched cavity dumped laser resonator. Under the absorbed pump power of 24.9 W, the pulse duration is adjustable from 31.9 ns to 5.9 ns by changing the amplitude of the high voltage on the inserted PC from 1100 V to 4400 V at the pulse repetition rate of 10 kHz. The corresponding average output power is almost entirely maintained in the range of 3.5–4.1 W. This represents more than three times increase in pulse duration tunable regime and average power compared to previously reported results for duration-tunable ns lasers. The laser beam quality factor was measured to be M 2  <  1.18.

  16. Surface modification of PET films using dielectric barrier discharge driven by repetitive nanosecond-pulses

    International Nuclear Information System (INIS)

    Shao Tao; Zhang Cheng; Long Kaihua; Wang Jue; Zhang Dongdong; Yan Ping; Zhou Yuanxiang

    2010-01-01

    In this paper, surface treatment of PET films for improving the hydrophilicity using DBD excited by unipolar nanosecond-pulses is presented. Homogeneous and filamentary discharge are obtained under certain experimental conditions and then used to modify the surface of PET films. The properties of PET films before and after treatment are characterized with water contact angle measurement, atomic force microscope and X-ray photoelectron spectroscope. The experimental results show that static water contact angles decrease after DBD plasma treatment and the observed contact angle is changed from 80 degree for the untreated samples to 20 degree after treatment. However, the decrease of contact angles is not continuous and it will reach a saturation state after certain treatment time. The improvement of surface hydrophilicity can be attributed to the enhancement of the surface roughness and introduction of oxygen-containing polar functional groups. In contrast with the filamentary DBD treatment, the homogenous DBD is more effective in PET surface treatment. (authors)

  17. Luminous phase of nanosecond discharge in deionized water: morphology, propagation velocity and optical emission.

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan; Pongrác, Branislav; Babický, Václav; Člupek, Martin; Lukeš, Petr

    2017-01-01

    Roč. 26, č. 7 (2017), č. článku 07LT01. ISSN 0963-0252 R&D Projects: GA ČR(CZ) GA15-12987S Institutional support: RVO:61389021 Keywords : water * nanosecond discharge * emission spectra * breakdown Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.302, year: 2016 http://iopscience.iop.org/article/10.1088/1361-6595/aa758d

  18. Electropermeabilization by uni- or bipolar nanosecond electric pulses: The impact of extracellular conductivity.

    Science.gov (United States)

    Gianulis, Elena C; Casciola, Maura; Xiao, Shu; Pakhomova, Olga N; Pakhomov, Andrei G

    2018-02-01

    Cellular effects caused by nanosecond electric pulses (nsEP) can be reduced by an electric field reversal, a phenomenon known as bipolar cancellation. The reason for this cancellation effect remains unknown. We hypothesized that assisted membrane discharge is the mechanism for bipolar cancellation. CHO-K1 cells bathed in high (16.1mS/cm; HCS) or low (1.8mS/cm; LCS) conductivity solutions were exposed to either one unipolar (300-ns) or two opposite polarity (300+300-ns; bipolar) nsEP (4-40kV/cm) with increasing interpulse intervals (0.1-50μs). Time-lapse YO-PRO-1 (YP) uptake revealed enhanced membrane permeabilization in LCS compared to HCS at all tested voltages. The time-dependence of bipolar cancellation was similar in both solutions, using either identical (22kV/cm) or isoeffective nsEP treatments (12 and 32kV/cm for LCS and HCS, respectively). However, cancellation was significantly stronger in LCS when the bipolar nsEP had no, or very short (bipolar cancellation was still present with interpulse intervals as long as 50μs, beyond the time expected for membrane discharge. Our findings do not support assisted membrane discharge as the mechanism for bipolar cancellation. Instead they exemplify the sustained action of nsEP that can be reversed long after the initial stimulus. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Faraday cup with nanosecond response and adjustable impedance for fast electron beam characterization

    International Nuclear Information System (INIS)

    Hu Jing; Rovey, Joshua L.

    2011-01-01

    A movable Faraday cup design with simple structure and adjustable impedance is described in this work. This Faraday cup has external adjustable shunt resistance for self-biased measurement setup and 50 Ω characteristic impedance to match with 50 Ω standard BNC coaxial cable and vacuum feedthroughs for nanosecond-level pulse signal measurements. Adjustable shunt resistance allows self-biased measurements to be quickly acquired to determine the electron energy distribution function. The performance of the Faraday cup is validated by tests of response time and amplitude of output signal. When compared with a reference source, the percent difference of the Faraday cup signal fall time is less than 10% for fall times greater than 10 ns. The percent difference of the Faraday cup signal pulse width is below 6.7% for pulse widths greater than 10 ns. A pseudospark-generated electron beam is used to compare the amplitude of the Faraday cup signal with a calibrated F-70 commercial current transformer. The error of the Faraday cup output amplitude is below 10% for the 4-14 kV tested pseudospark voltages. The main benefit of this Faraday cup is demonstrated by adjusting the external shunt resistance and performing the self-biased method for obtaining the electron energy distribution function. Results from a 4 kV pseudospark discharge indicate a ''double-humped'' energy distribution.

  20. Faraday cup with nanosecond response and adjustable impedance for fast electron beam characterization.

    Science.gov (United States)

    Hu, Jing; Rovey, Joshua L

    2011-07-01

    A movable Faraday cup design with simple structure and adjustable impedance is described in this work. This Faraday cup has external adjustable shunt resistance for self-biased measurement setup and 50 Ω characteristic impedance to match with 50 Ω standard BNC coaxial cable and vacuum feedthroughs for nanosecond-level pulse signal measurements. Adjustable shunt resistance allows self-biased measurements to be quickly acquired to determine the electron energy distribution function. The performance of the Faraday cup is validated by tests of response time and amplitude of output signal. When compared with a reference source, the percent difference of the Faraday cup signal fall time is less than 10% for fall times greater than 10 ns. The percent difference of the Faraday cup signal pulse width is below 6.7% for pulse widths greater than 10 ns. A pseudospark-generated electron beam is used to compare the amplitude of the Faraday cup signal with a calibrated F-70 commercial current transformer. The error of the Faraday cup output amplitude is below 10% for the 4-14 kV tested pseudospark voltages. The main benefit of this Faraday cup is demonstrated by adjusting the external shunt resistance and performing the self-biased method for obtaining the electron energy distribution function. Results from a 4 kV pseudospark discharge indicate a "double-humped" energy distribution.

  1. A compact nanosecond pulse generator for DBD tube characterization

    Science.gov (United States)

    Rai, S. K.; Dhakar, A. K.; Pal, U. N.

    2018-03-01

    High voltage pulses of very short duration and fast rise time are required for generating uniform and diffuse plasma under various operating conditions. Dielectric Barrier Discharge (DBD) has been generated by high voltage pulses of short duration and fast rise time to produce diffuse plasma in the discharge gap. The high voltage pulse power generators have been chosen according to the requirement for the DBD applications. In this paper, a compact solid-state unipolar pulse generator has been constructed for characterization of DBD plasma. This pulsar is designed to provide repetitive pulses of 315 ns pulse width, pulse amplitude up to 5 kV, and frequency variation up to 10 kHz. The amplitude of the output pulse depends on the dc input voltage. The output frequency has been varied by changing the trigger pulse frequency. The pulsar is capable of generating pulses of positive or negative polarity by changing the polarity of pulse transformer's secondary. Uniform and stable homogeneous dielectric barrier discharge plasma has been produced successfully in a xenon DBD tube at 400-mbar pressure using the developed high voltage pulse generator.

  2. Rise time of proton cut-off energy in 2D and 3D PIC simulations

    Science.gov (United States)

    Babaei, J.; Gizzi, L. A.; Londrillo, P.; Mirzanejad, S.; Rovelli, T.; Sinigardi, S.; Turchetti, G.

    2017-04-01

    The Target Normal Sheath Acceleration regime for proton acceleration by laser pulses is experimentally consolidated and fairly well understood. However, uncertainties remain in the analysis of particle-in-cell simulation results. The energy spectrum is exponential with a cut-off, but the maximum energy depends on the simulation time, following different laws in two and three dimensional (2D, 3D) PIC simulations so that the determination of an asymptotic value has some arbitrariness. We propose two empirical laws for the rise time of the cut-off energy in 2D and 3D PIC simulations, suggested by a model in which the proton acceleration is due to a surface charge distribution on the target rear side. The kinetic energy of the protons that we obtain follows two distinct laws, which appear to be nicely satisfied by PIC simulations, for a model target given by a uniform foil plus a contaminant layer that is hydrogen-rich. The laws depend on two parameters: the scaling time, at which the energy starts to rise, and the asymptotic cut-off energy. The values of the cut-off energy, obtained by fitting 2D and 3D simulations for the same target and laser pulse configuration, are comparable. This suggests that parametric scans can be performed with 2D simulations since 3D ones are computationally very expensive, delegating their role only to a correspondence check. In this paper, the simulations are carried out with the PIC code ALaDyn by changing the target thickness L and the incidence angle α, with a fixed a0 = 3. A monotonic dependence, on L for normal incidence and on α for fixed L, is found, as in the experimental results for high temporal contrast pulses.

  3. Design of peptide substrates for nanosecond time-resolved fluorescence assays of proteases: 2,3-diazabicyclo[2.2.2]oct-2-ene as a noninvasive fluorophore.

    Science.gov (United States)

    Hennig, Andreas; Florea, Mara; Roth, Doris; Enderle, Thilo; Nau, Werner M

    2007-01-15

    Fluorescence protease assays were investigated with peptide substrates containing a 2,3-diazabicyclo[2.2.2]oct-2-ene-labeled asparagine (Dbo) as a fluorescent amino acid. The special characteristic of the fluorophore Dbo is its exceedingly long fluorescence lifetime (ca. 300 ns in water under air), which allows the use of nanosecond time-resolved fluorescence (Nano-TRF) detection to efficiently suppress shorter-lived background emission. In addition, the natural amino acids tryptophan and tyrosine can be employed as intramolecular fluorescence quenchers, which facilitates substrate design. Fourteen synthetic peptide substrates (composed of 2-19 amino acids) and five enzymes (trypsin, pepsin, carboxypeptidase A, leucine aminopeptidase, and chymotrypsin) were investigated and, in all 28 examined combinations, enzymatic activity was detected by monitoring the increase in steady state fluorescence with time and determining the reaction rates as kcat/Km values, which ranged from 0.2 to 80x10(6) M-1 min-1. The results suggest an excellent compatibility of the very small and hydrophilic fluorescent probe Dbo with solid-phase peptide synthesis and the investigated proteases. For all 14 peptides the fluorescence lifetimes before and after enzymatic cleavage were measured and Nano-TRF measurements were performed in 384-well microplates. The fluorescence lifetimes of the different peptides provide the basis for the rational design of Dbo-based fluorescent substrates for protease assays. Measurements in Nano-TRF mode revealed, in addition to efficient suppression of background fluorescence, an increased differentiation between cleaved and uncleaved substrate. The Dbo-based assays can be adapted for high-throughput screening.

  4. Thermally assisted nanosecond laser generation of ferric nanoparticles

    Science.gov (United States)

    Kurselis, K.; Kozheshkurt, V.; Kiyan, R.; Chichkov, B.; Sajti, L.

    2018-03-01

    A technique to increase nanosecond laser based production of ferric nanoparticles by elevating temperature of the iron target and controlling its surface exposure to oxygen is reported. High power near-infrared laser ablation of the iron target heated up to 600 °C enhances the particle generation efficiency by more than tenfold exceeding 6 μg/J. Temporal and thermal dependencies of the particle generation process indicate correlation of this enhancement with the oxidative processes that take place on the iron surface during the per spot interpulse delay. Nanoparticles, produced using the heat-assisted ablation technique, are examined using scanning electron and transmission electron microscopy confirming the presence of 1-100 nm nanoparticles with an exponential size distribution that contain multiple randomly oriented magnetite nanocrystallites. The described process enables the application of high power lasers and facilitates precise, uniform, and controllable direct deposition of ferric nanoparticle coatings at the industry-relevant rates.

  5. Novel X-ray imaging diagnostics of high energy nanosecond pulse accelerators

    International Nuclear Information System (INIS)

    Smith, Graham W.; Gallegos, Roque Rosauro; Hohlfelder, Robert James; Beutler, David Eric; Dudley, John; Seymour, Calvin L.G.; Bell, John D.

    2004-01-01

    Pioneering x-ray imaging has been undertaken on a number of AWE's and Sandia National Laboratories radiation effects x-ray simulators. These simulators typically yield a single very short (<50ns) pulse of high-energy (MeV endpoint energy bremsstrahlung) x-ray radiation with doses in the kilorad (krad(Si)) region. X-ray source targets vary in size from 2 to 25cm diameter, dependent upon the particular simulator. Electronic imaging of the source x-ray emission under dynamic conditions yields valuable information upon how the simulator is performing. The resultant images are of interest to the simulator designer who may configure new x-ray source converter targets and diode designs. The images can provide quantitative information about machine performance during radiation effects testing of components under active conditions. The effects testing program is a valuable interface for validation of high performance computer codes and models for the radiation effects community. A novel high-energy x-ray imaging spectrometer is described whereby the spectral energy (0.1 to 2.5MeV) profile may be discerned from the digitally recorded and viewable images via a pinhole/scintillator/CCD imaging system and knowledge of the filtration parameters. Unique images, analysis and a preliminary evaluation of the capability of the spectrometer are presented. Further, a novel time resolved imaging system is described that captures a sequence of high spatial resolution temporal images, with zero interframe time, in the nanosecond timeframe, of our source x-rays.

  6. Two-stage optical parametric chirped-pulse amplifier using sub-nanosecond pump pulse generated by stimulated Brillouin scattering compression

    Science.gov (United States)

    Ogino, Jumpei; Miyamoto, Sho; Matsuyama, Takahiro; Sueda, Keiichi; Yoshida, Hidetsugu; Tsubakimoto, Koji; Miyanaga, Noriaki

    2014-12-01

    We demonstrate optical parametric chirped-pulse amplification (OPCPA) based on two-beam pumping, using sub-nanosecond pulses generated by stimulated Brillouin scattering compression. Seed pulse energy, duration, and center wavelength were 5 nJ, 220 ps, and ˜1065 nm, respectively. The 532 nm pulse from a Q-switched Nd:YAG laser was compressed to ˜400 ps in heavy fluorocarbon FC-40 liquid. Stacking of two time-delayed pump pulses reduced the amplifier gain fluctuation. Using a walk-off-compensated two-stage OPCPA at a pump energy of 34 mJ, a total gain of 1.6 × 105 was obtained, yielding an output energy of 0.8 mJ. The amplified chirped pulse was compressed to 97 fs.

  7. Barrier response to Holocene sea-level rise

    DEFF Research Database (Denmark)

    Pejrup, Morten; Andersen, Thorbjørn Joest; Johannessen, Peter N

    Normally it is believed that sea-level rise causes coastal barrier retreat. However, sea-level is only one of the parameters determining the long term coastal development of barrier coasts. Sediment supply is an equally important determinant and may overshadow the effects of sea-level rise....... Conceptually this has been known for a long time but for the first time we can show the relative effect of these two parameters. We have studied three neighboring barrier islands in the Wadden Sea, and described their 3D morphological evolution during the last 8000 years. It appears that the barrier islands...... a much stronger component of sea-level control. The distance between the islands is only 50 km, and therefore our study shows that prediction of barrier development during a period of rising sea level may be more complicated than formerly believed....

  8. Effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier

    International Nuclear Information System (INIS)

    Song Rui; Hou Jing; Wang Ze-Feng; Lu Qi-Sheng; Xiao Rui

    2013-01-01

    Theoretical and experimental research on the effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier is carried out. The complex Ginzburg—Landau equation is used to simulate the propagation of the pulse in the fiber amplifier and the results show that pulses with negative initial chirp produce the widest supercontinuum and pulses with positive initial chirp produce the narrowest supercontinuum when the central wavelength of the pump lies in the normal dispersion region of the gain fiber. A self-made line width narrowing system is utilized to control the initial chirp of the nanosecond pump pulse and a four-stage master oscillator power amplifier configuration is adopted to produce a high power near-infrared suppercontinuum. The experimental results are in good agreement with simulations which can provide some guidance on further optimization of the system in future work. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  9. submitter 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

    CERN Document Server

    Gundacker, Stefan; Pauwels, Kristof; Lecoq, Paul

    2016-01-01

    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 (${{\\tau}_{d}}$ ) and the number of photons detected (${{n}^{\\prime}}$ ), i.e. $CTR\\propto \\sqrt{{{\\tau}_{d}}/{{n}^{\\prime}}}$ . However, it is still an open question to what extent the scintillation rise time (${{\\tau}_{r}}$ ) 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, promp...

  10. Comparative evaluation of transmembrane ion transport due to monopolar and bipolar nanosecond, high-intensity electroporation pulses based on full three-dimensional analyses

    Science.gov (United States)

    Hu, Q.; Joshi, R. P.

    2017-07-01

    Electric pulse driven membrane poration finds applications in the fields of biomedical engineering and drug/gene delivery. Here we focus on nanosecond, high-intensity electroporation and probe the role of pulse shape (e.g., monopolar-vs-bipolar), multiple electrode scenarios, and serial-versus-simultaneous pulsing, based on a three-dimensional time-dependent continuum model in a systematic fashion. Our results indicate that monopolar pulsing always leads to higher and stronger cellular uptake. This prediction is in agreement with experimental reports and observations. It is also demonstrated that multi-pronged electrode configurations influence and increase the degree of cellular uptake.

  11. Activation of Anti-tumor Immune Response by Ablation of HCC with Nanosecond Pulsed Electric Field.

    Science.gov (United States)

    Xu, Xiaobo; Chen, Yiling; Zhang, Ruiqing; Miao, Xudong; Chen, Xinhua

    2018-03-28

    Locoregional therapy is playing an increasingly important role in the non-surgical management of hepatocellular carcinoma (HCC). The novel technique of non-thermal electric ablation by nanosecond pulsed electric field has been recognized as a potential locoregional methodology for indicated HCC. This manuscript explores the most recent studies to indicate its unique anti-tumor immune response. The possible immune mechanism, termed as nano-pulse stimulation, was also analyzed.

  12. A 800 kV compact peaking capacitor for nanosecond generator.

    Science.gov (United States)

    Jia, Wei; Chen, Zhiqiang; Tang, Junping; Chen, Weiqing; Guo, Fan; Sun, Fengrong; Li, Junna; Qiu, Aici

    2014-09-01

    An extremely compact high voltage peaking capacitor is developed. The capacitor has a pancake structure with a diameter of 315 mm, a thickness of 59 mm, and a mass of 6.1 kg. The novel structural design endows the capacitor with a better mechanical stability and reliability under hundreds of kilovolts pulse voltage and an inner gas pressure of more than 1.5 MPa. The theoretical value of the capacitor self-inductance is near to 17 nH. Proved by series of electrical experiments, the capacitor can endure a high-voltage pulse with a rise time of about 20 ns, a half-width duration of around 25 ns, and an amplitude of up to 800 kV in a single shot model. When the capacitor was used in an electromagnetic pulse simulator as a peaking capacitor, the rise time of the voltage pulse can be reduced from 20 ns to less than 3 ns. The practical value of the capacitor's inductance deduced from the experimental date is no more than 25 nH.

  13. 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

    International Nuclear Information System (INIS)

    Kalluri, D.K.

    1996-01-01

    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 ω p (t) with a rise time T r . If the period t 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 0 is comparable to the rise time T 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 1 to 10 3 /cc in a rise time of about 100 micros

  14. Control of Reactive Species Generated by Low-frequency Biased Nanosecond Pulse Discharge in Atmospheric Pressure Plasma Effluent

    Science.gov (United States)

    Takashima, Keisuke; Kaneko, Toshiro

    2016-09-01

    The control of hydroxyl radical and the other gas phase species generation in the ejected gas through air plasma (air plasma effluent) has been experimentally studied, which is a key to extend the range of plasma treatment. Nanosecond pulse discharge is known to produce high reduced electric field (E/N) discharge that leads to efficient generation of the reactive species than conventional low frequency discharge, while the charge-voltage cycle in the low frequency discharge is known to be well-controlled. In this study, the nanosecond pulse discharge biased with AC low frequency high voltage is used to take advantages of these discharges, which allows us to modulate the reactive species composition in the air plasma effluent. The utilization of the gas-liquid interface and the liquid phase chemical reactions between the modulated long-lived reactive species delivered from the air plasma effluent could realize efficient liquid phase chemical reactions leading to short-lived reactive species production far from the air plasma, which is crucial for some plasma agricultural applications.

  15. Simulation of transformations of thin metal films heated by nanosecond laser pulses

    Science.gov (United States)

    Balandin, V. Yu.; Niedrig, R.; Bostanjoglo, O.

    1995-01-01

    The ablation of free-standing thin aluminum films by a nanosecond laser pulse was investigated by time-resolved transmission electron microscopy and numerical simulation. It was established that thin film geometry is particularly suited to furnish information on the mechanism of evaporation and the surface tension of the melt. In the case of aluminum the surface tension sigma as function of temperature can be approximated by two linear sections with a coefficient -0.3 x 10(exp -3) N/K m from the melting point 933 K up to 3000 K and -0.02 x 10(exp -3) N/K m above 3000 K, respectively, with sigma(993 K) = 0.9 N/m and sigma(8500 K) = 0. At lower pulse energies the films disintegrated predominantly by thermocapillary flow. Higher pulse energies produced volume evaporation, and a nonmonotonous flow, explained by recoil from evaporating atoms and thermocapillarity. The familiar equations of energy and motion, which presuppose separate and coherent vapor and liquid phases, were not adequate to describe the ablation of the hottest zone. Surface evaporation seemed to be marginal at all laser pulse energies used.

  16. Detection of explosives and other illicit materials by a single nanosecond neutron pulses - Monte-Carlo simulations of the detection process

    International Nuclear Information System (INIS)

    Miklaszewski, R.; Drozdowicz, K.; Wiacek, U.; Dworak, D.; Gribkov, V.

    2011-01-01

    Recent progress in the development of a single-pulse Nanosecond Impulse Neutron Investigation System (NINIS) intended for interrogation of hidden objects (explosives and other illicit materials) by means of measuring elastically scattered neutrons is presented in this paper. The method is based on the well know fact that nuclide-specific information is present in the scattered neutron field. The method uses very bright neutron pulses having duration of the order of few nanoseconds, generated by a dense plasma focus (DPF) devices filled with a pure deuterium or deuterium-tritium mixture as a working gas. Very short duration of the neutron pulse, its high brightness and mono-chromaticity allow to use the time-of-flight method with bases of about few meters to distinguish signals from neutrons scattered by different elements. Results of the Monte Carlo simulations of the scattered neutron field from several compounds (explosives and everyday use materials) are presented in the paper. The MCNP5 code has been used to get information on the angular and energy distributions of the neutrons scattered by the above mentioned compounds assuming the initial neutron energy equal to 2.45 MeV (D-D). A new input has been elaborated that allows the modelling of not only a spectrum of the neutrons scattered at different angles but also their time history from the moment of generation up to detection. Such an approach allows getting approximate signals as registered by scintillator + photomultiplier probes placed at various distances from the scattering object, demonstrating a principal capability of the method to identify an elemental content of the inspected objects. Preliminary results of the MCNP modelling of the interrogation process of the airport luggage containing several illicit objects are presented as well. (authors)

  17. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    KAUST Repository

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan L; Cha, Min

    2016-01-01

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble

  18. Nanosecond laser-induced synthesis of nanoparticles with tailorable magneticanisotropy

    International Nuclear Information System (INIS)

    Krishna, H.; Gangopadhyay, A.K.; Strader, J.; Kalyanaraman, R.

    2011-01-01

    Controlling the magnetic orientation of nanoparticles is important for many applications. Recently, it has been shown that single domain ferromagnetic hemispherical Co nanoparticles prepared by nanosecond laser-induced self-organization, show magnetic orientation that was related to the negative sign of the magnetostrictive coefficient λ S [J. Appl. Phys. v103, p073902, 2008]. Here we have extended this work to the Fe 50 Co 50 alloy, which has a positive λ S and Ni, which has a negative λ S . Patterned arrays of ferromagnetic nanoparticles of Fe 50 Co 50 , Ni, (and Co) were synthesized from their ultrathin metal films on SiO 2 substrate by nanosecond laser-induced self-organization. The morphology, nanostructure, and magnetic behavior of the nanoparticle arrays were investigated by a combination of electron microscopy, atomic force microscopy, and magnetic force microscopy techniques. Transmission electron microscopy investigations revealed a granular polycrystalline nanostructure, with the number of grains inside the nanoparticle increasing with their diameter. Magnetic force measurements showed that the magnetization direction of the hemispherical Co and Ni nanoparticles was predominantly out-of-plane while those for the Fe 50 Co 50 alloy was in the plane of the substrate. Finite element analysis was used to estimate the average residual strain in the nanoparticles, following laser processing. The difference in behavior is due to the dominating influence of magnetostrictive energy on the magnetization as a result of residual thermal strain following fast laser processing. Since λ S is negative for polycrystalline Co and Ni, and positive for Fe 50 Co 50 , the tensile residual strain forces the magnetization direction to out-of-plane and in-plane, respectively. This work demonstrates a cost-effective non-epitaxial technique for the synthesis of magnetic nanoparticles with tailored magnetization orientations. - Research Highlights: → Pulsed laser self

  19. Fundamental Physics and Engineering of Nanosecond-Pulsed Nonequilibrium Microplasma in Liquid Phase without Bubbles

    Science.gov (United States)

    2013-01-04

    the electrode, the value   coth0  a corresponds to an equipotential surface which coincides with the electrode;  is the ratio of the semiaxes...liquid when filled – see Figure 1. The liquid surface was left open to the air, subject to atmospheric pressure. Nanosecond pulse generators from...temperature T , k is the Boltzmann constant,  is the surface tension coefficient, J is the nucleation rate equal to the density of vapor bubbles of a

  20. PIC simulations of post-pulse field reversal and secondary ionization in nanosecond argon discharges

    Science.gov (United States)

    Kim, H. Y.; Gołkowski, M.; Gołkowski, C.; Stoltz, P.; Cohen, M. B.; Walker, M.

    2018-05-01

    Post-pulse electric field reversal and secondary ionization are investigated with a full kinetic treatment in argon discharges between planar electrodes on nanosecond time scales. The secondary ionization, which occurs at the falling edge of the voltage pulse, is induced by charge separation in the bulk plasma region. This process is driven by a reverse in the electric field from the cathode sheath to the formerly driven anode. Under the influence of the reverse electric field, electrons in the bulk plasma and sheath regions are accelerated toward the cathode. The electron movement manifests itself as a strong electron current generating high electron energies with significant electron dissipated power. Accelerated electrons collide with Ar molecules and an increased ionization rate is achieved even though the driving voltage is no longer applied. With this secondary ionization, in a single pulse (SP), the maximum electron density achieved is 1.5 times higher and takes a shorter time to reach using 1 kV 2 ns pulse as compared to a 1 kV direct current voltage at 1 Torr. A bipolar dual pulse excitation can increase maximum density another 50%–70% above a SP excitation and in half the time of RF sinusoidal excitation of the same period. The first field reversal is most prominent but subsequent field reversals also occur and correspond to electron temperature increases. Targeted pulse designs can be used to condition plasma density as required for fast discharge applications.

  1. Study of emission of a volume nanosecond discharge plasma in xenon, krypton and argon at high pressures

    International Nuclear Information System (INIS)

    Baksht, E Kh; Lomaev, Mikhail I; Rybka, D V; Tarasenko, Viktor F

    2006-01-01

    The emission properties of a volume nanosecond discharge plasma produced in xenon, krypton and argon at high pressures in a discharge gap with a cathode having a small radius of curvature are studied. Spectra in the range 120-850 nm and amplitude-time characteristics of xenon emission at different regimes and excitation techniques are recorded and analysed. It is shown that upon excitation of the volume discharge initiated by a beam of avalanche electrons, at least 90% of the energy in the spectral range 120-850 nm is emitted by xenon dimers. For xenon at a pressure of 1.2 atm, ∼45 mJ of the spontaneous emission energy was obtained in the full solid angle in a pulse with the full width at half-maximum ∼130 ns. (laser applications and other topics in quantum electronics)

  2. Nanosecond Pulsed Discharge in Water without Bubbles: A Fundamental Study of Initiation, Propagation and Plasma Characteristics

    Science.gov (United States)

    Seepersad, Yohan

    The state of plasma is widely known as a gas-phase phenomenon, but plasma in liquids have also received significant attention over the last century. Generating plasma in liquids however is theoretically challenging, and this problem is often overcome via liquid-gas phase transition preceding the actual plasma formation. In this sense, plasma forms in gas bubbles in the liquid. Recent work at the Drexel Plasma Institute has shown that nanosecond pulsed electric fields can initiate plasma in liquids without any initial cavitation phase, at voltages below theoretical direct-ionization thresholds. This unique regime is poorly understood and does not fit into any current descriptive mechanisms. As with all new phenomena, a complete fundamental description is paramount to understanding its usefulness to practical applications. The primary goals of this research were to qualitatively and quantitatively understand the phenomenon of nanosecond pulsed discharge in liquids as a means to characterizing properties that may open up niche application possibilities. Analysis of the plasma was based on experimental results from non-invasive, sub-nanosecond time-resolved optical diagnostics, including direct imaging, transmission imaging (Schlieren and shadow), and optical emission spectroscopy. The physical characteristics of the plasma were studied as a function of variations in the electric field amplitude and polarity, liquid permittivity, and pulse duration. It was found that the plasma size and emission intensity was dependent on the permittivity of the liquid, as well as the voltage polarity, and the structure and dynamics were explained by a 'cold-lightning' mechanism. The under-breakdown dynamics at the liquid-electrode interface were investigated by transmission imaging to provide evidence for a novel mechanism for initiation based on the electrostriction. This mechanism was proposed by collaborators on the project and developed alongside the experimental work in this

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

    CERN Document Server

    Troyer, G L

    2000-01-01

    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 r...

  4. Supershort avalanche electron beam in SF_{6} and krypton

    Directory of Open Access Journals (Sweden)

    Cheng Zhang (章程

    2016-03-01

    Full Text Available Runaway electrons play an important role in the avalanche formation in nanosecond- and subnanosecond- pulse discharges. In this paper, characteristics of a supershort avalanche electron beam (SAEB generated at the subnanosecond and nanosecond breakdown in sulfur hexafluoride (SF_{6} in an inhomogeneous electric field were studied. One pulser operated at negative polarity with voltage pulse amplitude of ∼130  kV and rise time of 0.3 ns. The other pulser operated at negative polarity with voltage pulse amplitude of 70 kV and rise time of ∼1.6  ns. SAEB parameters in SF_{6} are compared with those obtained in krypton (Kr, nitrogen (N_{2}, air, and mixtures of SF_{6} with krypton or nitrogen. Experimental results showed that SAEB currents appeared during the rise-time of the voltage pulse for both pulsers. Moreover, amplitudes of the SAEB current in SF_{6} and Kr approximately ranged from several to tens of milliamps at atmospheric pressure, which were smaller than those in N_{2} and air (ranging from hundreds of milliamps to several amperes. Furthermore, the concentration of SF_{6} additive could significantly reduce the SAEB current in N_{2}-SF_{6} mixture, but it slightly affected the SAEB current in Kr-SF_{6} mixture because of the atomic/molecular ionization cross section of the gas had a much greater impact on the SAEB current rather than the electronegativity.

  5. HiRISE: The People's Camera

    Science.gov (United States)

    McEwen, A. S.; Eliason, E.; Gulick, V. C.; Spinoza, Y.; Beyer, R. A.; HiRISE Team

    2010-12-01

    The High Resolution Imaging Science Experiment (HiRISE) camera, orbiting Mars since 2006 on the Mars Reconnaissance Orbiter (MRO), has returned more than 17,000 large images with scales as small as 25 cm/pixel. From it’s beginning, the HiRISE team has followed “The People’s Camera” concept, with rapid release of useful images, explanations, and tools, and facilitating public image suggestions. The camera includes 14 CCDs, each read out into 2 data channels, so compressed images are returned from MRO as 28 long (up to 120,000 line) images that are 1024 pixels wide (or binned 2x2 to 512 pixels, etc.). This raw data is very difficult to use, especially for the public. At the HiRISE operations center the raw data are calibrated and processed into a series of B&W and color products, including browse images and JPEG2000-compressed images and tools to make it easy for everyone to explore these enormous images (see http://hirise.lpl.arizona.edu/). Automated pipelines do all of this processing, so we can keep up with the high data rate; images go directly to the format of the Planetary Data System (PDS). After students visually check each image product for errors, they are fully released just 1 month after receipt; captioned images (written by science team members) may be released sooner. These processed HiRISE images have been incorporated into tools such as Google Mars and World Wide Telescope for even greater accessibility. 51 Digital Terrain Models derived from HiRISE stereo pairs have been released, resulting in some spectacular flyover movies produced by members of the public and viewed up to 50,000 times according to YouTube. Public targeting began in 2007 via NASA Quest (http://marsoweb.nas.nasa.gov/HiRISE/quest/) and more than 200 images have been acquired, mostly by students and educators. At the beginning of 2010 we released HiWish (http://www.uahirise.org/hiwish/), opening HiRISE targeting to anyone in the world with Internet access, and already more

  6. Measuring the diameter of rising gas bubbles by means of the ultrasound transit time technique

    Energy Technology Data Exchange (ETDEWEB)

    Richter, T., E-mail: Thomas.Richter6@tu-dresden.de; Eckert, K., E-mail: Kerstin.Eckert@tu-dresden.de; Yang, X.; Odenbach, S.

    2015-09-15

    Highlights: • Ultrasound transit time technique (UTTT) is applied to the zig-zag raise of gas bubble. • Comparison of bubble diameter and tilt, measured by UTTT, with high-speed imaging. • Uncertainty in the determination of the bubble diameter by UTTT is less than 7%. • UTTT is able to measure dynamic changes in bubble size in opaque liquids and vessels. • UTTT can be applied to liquid metal loops. - Abstract: This study presents ultrasound transit time technique (UTTT) measurements of the diameter variations of single argon bubbles rising in a zig-zag trajectory in water. Simultaneous size measurements with a high-speed camera show that UTTT resolves both the apparent diameter and the tilt of the bubble axis with an accuracy of better than 7%. This qualifies UTTT for the measurement of bubble sizes in opaque liquids, such as liquid metals, or vessels.

  7. Finite element method (FEM) model of the mechanical stress on phospholipid membranes from shock waves produced in nanosecond electric pulses (nsEP)

    Science.gov (United States)

    Barnes, Ronald; Roth, Caleb C.; Shadaram, Mehdi; Beier, Hope; Ibey, Bennett L.

    2015-03-01

    The underlying mechanism(s) responsible for nanoporation of phospholipid membranes by nanosecond pulsed electric fields (nsEP) remains unknown. The passage of a high electric field through a conductive medium creates two primary contributing factors that may induce poration: the electric field interaction at the membrane and the shockwave produced from electrostriction of a polar submersion medium exposed to an electric field. Previous work has focused on the electric field interaction at the cell membrane, through such models as the transport lattice method. Our objective is to model the shock wave cell membrane interaction induced from the density perturbation formed at the rising edge of a high voltage pulse in a polar liquid resulting in a shock wave propagating away from the electrode toward the cell membrane. Utilizing previous data from cell membrane mechanical parameters, and nsEP generated shockwave parameters, an acoustic shock wave model based on the Helmholtz equation for sound pressure was developed and coupled to a cell membrane model with finite-element modeling in COMSOL. The acoustic structure interaction model was developed to illustrate the harmonic membrane displacements and stresses resulting from shockwave and membrane interaction based on Hooke's law. Poration is predicted by utilizing membrane mechanical breakdown parameters including cortical stress limits and hydrostatic pressure gradients.

  8. Analysis of copper contamination in transformer insulating material with nanosecond- and femtosecond-laser-induced breakdown spectroscopy

    Science.gov (United States)

    Aparna, N.; Vasa, N. J.; Sarathi, R.

    2018-06-01

    This work examines the oil-impregnated pressboard insulation of high-voltage power transformers, for the determination of copper contamination. Nanosecond- and femtosecond-laser-induced breakdown spectroscopy revealed atomic copper lines and molecular copper monoxide bands due to copper sulphide diffusion. X-ray diffraction studies also indicated the presence of CuO emission. Elemental and molecular mapping compared transformer insulating material ageing in different media—air, N2, He and vacuum.

  9. Interaction Of CO2 Laser Nanosecond Pulse Train With The Metallic Targets In Optical Breakdown Regime

    Science.gov (United States)

    Apollonov, V. V.; Firsov, K. N.; Konov, V. I.; Nikitin, P. I.; Prokhorov, A. M.; Silenok, A. S.; Sorochenko, V. R.

    1986-11-01

    In the present paper the electric field and currents in the air-breakdown plasma, produced by the train of nanosecond pulses of TEA-002 - regenerative amplifier near the un-charged targets are studied. The breakdown thresholds and the efficiency of plasma-target heat transmission are also measured. The results of numerical calculations made for increasing of the pulse train contrast with respect to the background in a regenerative amplifier are advanced.

  10. Finding Rising and Falling Words

    NARCIS (Netherlands)

    Tjong Kim Sang, E.

    2016-01-01

    We examine two different methods for finding rising words (among which neologisms) and falling words (among which archaisms) in decades of magazine texts (millions of words) and in years of tweets (billions of words): one based on correlation coefficients of relative frequencies and time, and one

  11. Investigation of the fundamentals of low-energy nanosecond pulse ignition: Final CRADA Report

    Energy Technology Data Exchange (ETDEWEB)

    Wallner, Thomas [Argonne National Lab. (ANL), Argonne, IL (United States); Scarcelli, Riccardo [Argonne National Lab. (ANL), Argonne, IL (United States); Zhang, Anqi [Argonne National Lab. (ANL), Argonne, IL (United States); Sevik, James [Argonne National Lab. (ANL), Argonne, IL (United States); Biruduganti, Munidhar [Argonne National Lab. (ANL), Argonne, IL (United States); Bihari, Bipin [Argonne National Lab. (ANL), Argonne, IL (United States); Matusik, Katarzyna E. [Argonne National Lab. (ANL), Argonne, IL (United States); Duke, Daniel J. [Argonne National Lab. (ANL), Argonne, IL (United States); Powell, Christopher F. [Argonne National Lab. (ANL), Argonne, IL (United States); Kastengren, Alan L. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-01-01

    A detailed investigation of the fundamentals of low-energy nanosecond pulse ignition was performed with the objective to overcome the barrier presented by limited knowledge and characterization of nonequilibrium plasma ignition for realistic internal combustion engine applications (be it in the automotive or power generation field) and shed light on the mechanisms which improve the performance of the advanced TPS ignition system compared to conventional state-of-the-art hardware. Three main tasks of the research included experimental evaluation on a single-cylinder automotive gasoline engine, experimental evaluation on a single-cylinder stationary natural gas engine and energy quantification using x-ray diagnostics.

  12. Trends in nanosecond melanosome microcavitation up to 1540 nm

    Science.gov (United States)

    Schmidt, Morgan S.; Kennedy, Paul K.; Noojin, Gary D.; Vincelette, Rebecca L.; Thomas, Robert J.; Rockwell, Benjamin A.

    2015-09-01

    Thresholds for microcavitation of bovine and porcine melanosomes were previously reported, using single nanosecond (ns) laser pulses in the visible (532 nm) and the near-infrared (NIR) from 1000 to 1319 nm. Here, we report average radiant exposure thresholds for bovine melanosome microcavitation at additional NIR wavelengths up to 1540 nm, which range from ˜0.159 J/cm2 at 800 nm to 4.5 J/cm2 at 1540 nm. Melanosome absorption coefficients were also estimated, and decreased with increasing wavelength. These values were compared to retinal pigment epithelium coefficients, and to water absorption, over the same wavelength range. Corneal total intraocular energy retinal damage threshold values were estimated and compared to the previous (2007) and recently changed (2014) maximum permissible exposure (MPE) safe levels. Results provide additional data that support the recent changes to the MPE levels, as well as the first microcavitation data at 1540 nm, a wavelength for which melanosome microcavitation may be an ns-pulse skin damage mechanism.

  13. Few-nanosecond pulse switching with low write error for in-plane nanomagnets using the spin-Hall effect

    Science.gov (United States)

    Aradhya, Sriharsha; Rowlands, Graham; Shi, Shengjie; Oh, Junseok; Ralph, D. C.; Buhrman, Robert

    Magnetic random access memory (MRAM) using spin transfer torques (STT) holds great promise for replacing existing best-in-class memory technologies in several application domains. Research on conventional two-terminal STT-MRAM thus far has revealed the existence of limitations that constrain switching reliability and speed for both in-plane and perpendicularly magnetized devices. Recently, spin torque arising from the giant spin-Hall effect in Ta, W and Pt has been shown to be an efficient mechanism to switch magnetic bits in a three-terminal geometry. Here we report highly reliable, nanosecond timescale pulse switching of three-terminal devices with in-plane magnetized magnetic tunnel junctions. We obtain write error rates (WER) down to ~10-5 using pulses as short as 2 ns, in contrast to conventional in-plane STT-MRAM devices where write speeds were limited to a few tens of nanoseconds for comparable WER. Utilizing micro-magnetic simulations, we discuss the differences from conventional MRAM that allow for this unanticipated and significant performance improvement. Finally, we highlight the path towards practical application enabled by the ability to separately optimize the read and write pathways in three-terminal devices.

  14. Electric field measurements in a nanosecond pulse discharge in atmospheric air

    International Nuclear Information System (INIS)

    Simeni Simeni, Marien; Frederickson, Kraig; Lempert, Walter R; Adamovich, Igor V; Goldberg, Benjamin M; Zhang, Cheng

    2017-01-01

    The paper presents the results of temporally and spatially resolved electric field measurements in a nanosecond pulse discharge in atmospheric air, sustained between a razor edge high-voltage electrode and a plane grounded electrode covered by a thin dielectric plate. The electric field is measured by picosecond four-wave mixing in a collinear phase-matching geometry, with time resolution of approximately 2 ns, using an absolute calibration provided by measurements of a known electrostatic electric field. The results demonstrate electric field offset on the discharge center plane before the discharge pulse due to surface charge accumulation on the dielectric from the weaker, opposite polarity pre-pulse. During the discharge pulse, the electric field follows the applied voltage until ‘forward’ breakdown occurs, after which the field in the plasma is significantly reduced due to charge separation. When the applied voltage is reduced, the field in the plasma reverses direction and increases again, until the weak ‘reverse’ breakdown occurs, producing a secondary transient reduction in the electric field. After the pulse, the field is gradually reduced on a microsecond time scale, likely due to residual surface charge neutralization by transport of opposite polarity charges from the plasma. Spatially resolved electric field measurements show that the discharge develops as a surface ionization wave. Significant surface charge accumulation on the dielectric surface is detected near the end of the discharge pulse. Spatially resolved measurements of electric field vector components demonstrate that the vertical electric field in the surface ionization wave peaks ahead of the horizontal electric field. Behind the wave, the vertical field remains low, near the detection limit, while the horizontal field is gradually reduced to near the detection limit at the discharge center plane. These results are consistent with time-resolved measurements of electric field

  15. Balanced cross-rate model for saturated molecular fluorescence in flames using a nanosecond pulse length laser

    International Nuclear Information System (INIS)

    Lucht, R.P.; Sweeney, D.W.; Laurendeau, N.M.

    1980-01-01

    The balanced cross-rate model is proposed to analyze laser-induced molecular fluorescence signals when the laser pulse length is of the order of nanoseconds. Nanosecond pulse length lasers. specifically Q-switched Nd:YAG-pumped dye lasers, are attractive for saturated molecular fluorescence spectroscopy because of their high peak power and because of their short pulse length minimizes the risk of laser-induced chemistry. In the balanced cross-rate model, single upper and lower rotational levels are assumed to be directly coupled by the laser radiation. Because the laser-induced processes which couple these levels are so fast at saturation intensities, a steady state is established between the two levels within picoseconds. Provided that the total population of the two laser-coupled rotational levels is constant during the laser pulse, the total molecular population can be calculated from the observed upper rotational level population using a two-level saturation model and Boltzmann statistics. Numerical simulation of the laser excitation dynamics of OH in an atmospheric pressure H 2 /O 2 /N 2 flame indicates that the balanced cross-rate model will give accurate results provided that the rotational relaxation rates in the upper and lower sets of rotational levels are approximately equal

  16. Study on processing parameters of glass cutting by nanosecond 532 nm fiber laser

    Science.gov (United States)

    Wang, Jin; Gao, Fan; Xiong, Baoxing; Zhang, Xiang; Yuan, Xiao

    2018-03-01

    The processing parameters of soda-lime glass cutting with several nanosecond 532 nm pulsed fiber laser are studied in order to obtain sufficiently large ablation rate and better processing quality. The influences of laser processing parameters on effective cutting speed and cutting quality of 1 2 mm thick soda-lime glass are studied. The experimental results show that larger laser pulse energy will lead to higher effective cutting speed and larger maximum edge collapse of the front side of the glass samples. Compared with that of 1.1 mm thick glass samples, the 2.0 mm thick glass samples is more difficult to cut. With the pulse energy of 51.2 μJ, the maximum edge collapse is more than 200 μm for the 2.0 mm thick glass samples. In order to achieve the high effective cutting speed and good cutting quality at the same time, the dual energy overlapping method is used to obtain the better cutting performance for the 2.0 mm thick glass samples, and the cutting speed of 194 mm/s and the maximum edge collapse of less than 132 μm are realized.

  17. An ultrafast programmable electrical tester for enabling time-resolved, sub-nanosecond switching dynamics and programming of nanoscale memory devices

    Science.gov (United States)

    Shukla, Krishna Dayal; Saxena, Nishant; Manivannan, Anbarasu

    2017-12-01

    Recent advancements in commercialization of high-speed non-volatile electronic memories including phase change memory (PCM) have shown potential not only for advanced data storage but also for novel computing concepts. However, an in-depth understanding on ultrafast electrical switching dynamics is a key challenge for defining the ultimate speed of nanoscale memory devices that demands for an unconventional electrical setup, specifically capable of handling extremely fast electrical pulses. In the present work, an ultrafast programmable electrical tester (PET) setup has been developed exceptionally for unravelling time-resolved electrical switching dynamics and programming characteristics of nanoscale memory devices at the picosecond (ps) time scale. This setup consists of novel high-frequency contact-boards carefully designed to capture extremely fast switching transient characteristics within 200 ± 25 ps using time-resolved current-voltage measurements. All the instruments in the system are synchronized using LabVIEW, which helps to achieve various programming characteristics such as voltage-dependent transient parameters, read/write operations, and endurance test of memory devices systematically using short voltage pulses having pulse parameters varied from 1 ns rise/fall time and 1.5 ns pulse width (full width half maximum). Furthermore, the setup has successfully demonstrated strikingly one order faster switching characteristics of Ag5In5Sb60Te30 (AIST) PCM devices within 250 ps. Hence, this novel electrical setup would be immensely helpful for realizing the ultimate speed limits of various high-speed memory technologies for future computing.

  18. High voltage nanosecond generator with pulse repetition rate of 1,000 p.p.s.

    Energy Technology Data Exchange (ETDEWEB)

    Gubanov, V P; Korovin, S D; Stepchenko, A S [High Current Electronics Institute, Tomsk (Russian Federation)

    1997-12-31

    A compact high voltage nanosecond generator is described with a pulse repetition rate up to 1000 p.p.s. The generator includes a 30-Ohm coaxial forming line charged by a built-in Tesla transformer with a high coupling coefficient, and a high voltage (N{sub 2}) gas gap switch with gas blowing between the electrodes. The maximum forming line charge voltage is 450 kV, the pulse duration is about 4 ns, and its amplitude for a matched load is up to 200 kV. (author). 3 figs., 9 refs.

  19. Measurements and kinetic modeling of atomic species in fuel-oxidizer mixtures excited by a repetitive nanosecond pulse discharge

    Science.gov (United States)

    Winters, C.; Eckert, Z.; Yin, Z.; Frederickson, K.; Adamovich, I. V.

    2018-01-01

    This work presents the results of number density measurements of metastable Ar atoms and ground state H atoms in diluted mixtures of H2 and O2 with Ar, as well as ground state O atoms in diluted H2-O2-Ar, CH4-O2-Ar, C3H8-O2-Ar, and C2H4-O2-Ar mixtures excited by a repetitive nanosecond pulse discharge. The measurements have been made in a nanosecond pulse, double dielectric barrier discharge plasma sustained in a flow reactor between two plane electrodes encapsulated within dielectric material, at an initial temperature of 500 K and pressures ranging from 300 Torr to 700 Torr. Metastable Ar atom number density distribution in the afterglow is measured by tunable diode laser absorption spectroscopy, and used to characterize plasma uniformity. Temperature rise in the reacting flow is measured by Rayleigh scattering. H atom and O atom number densities are measured by two-photon absorption laser induced fluorescence. The results are compared with kinetic model predictions, showing good agreement, with the exception of extremely lean mixtures. O atoms and H atoms in the plasma are produced mainly during quenching of electronically excited Ar atoms generated by electron impact. In H2-Ar and O2-Ar mixtures, the atoms decay by three-body recombination. In H2-O2-Ar, CH4-O2-Ar, and C3H8-O2-Ar mixtures, O atoms decay in a reaction with OH, generated during H atom reaction with HO2, with the latter produced by three-body H atom recombination with O2. The net process of O atom decay is O  +  H  →  OH, such that the decay rate is controlled by the amount of H atoms produced in the discharge. In extra lean mixtures of propane and ethylene with O2-Ar the model underpredicts the O atom decay rate. At these conditions, when fuel is completely oxidized by the end of the discharge burst, the net process of O atom decay, O  +  O  →  O2, becomes nearly independent of H atom number density. Lack of agreement with the data at these conditions is

  20. Contemporary sea level rise.

    Science.gov (United States)

    Cazenave, Anny; Llovel, William

    2010-01-01

    Measuring sea level change and understanding its causes has considerably improved in the recent years, essentially because new in situ and remote sensing observations have become available. Here we report on most recent results on contemporary sea level rise. We first present sea level observations from tide gauges over the twentieth century and from satellite altimetry since the early 1990s. We next discuss the most recent progress made in quantifying the processes causing sea level change on timescales ranging from years to decades, i.e., thermal expansion of the oceans, land ice mass loss, and land water-storage change. We show that for the 1993-2007 time span, the sum of climate-related contributions (2.85 +/- 0.35 mm year(-1)) is only slightly less than altimetry-based sea level rise (3.3 +/- 0.4 mm year(-1)): approximately 30% of the observed rate of rise is due to ocean thermal expansion and approximately 55% results from land ice melt. Recent acceleration in glacier melting and ice mass loss from the ice sheets increases the latter contribution up to 80% for the past five years. We also review the main causes of regional variability in sea level trends: The dominant contribution results from nonuniform changes in ocean thermal expansion.

  1. Experimental Investigation of Pulsed Nanosecond Streamer Discharges for CO2 Reforming

    Science.gov (United States)

    Pachuilo, Michael; Levko, Dima; Raja, Laxminarayan; Varghese, Philip

    2016-09-01

    Rapid global industrialization has led to an increase in atmospheric greenhouse gases, specifically carbon dioxide levels. Plasmas present a great potential for efficient reforming of greenhouse gases. There are several plasma discharges which have been reported for reforming process: dielectric barrier discharges (DBD), microwave discharges, and glide-arcs. Microwave discharges have CO2 conversion energy efficiency of up to 40% at atmospheric conditions, while glide-arcs have 43% and DBD 2-10%. In our study, we analyze a single nanosecond pulsed cathode directed streamer discharge in CO2 at atmospheric pressure and temperature. We have conducted time resolved imaging with spectral bandpass filters of a streamer discharge with an applied negative polarity pulse. The image sequences have been correlated to the applied voltage and current pulses. From the spectral filters we can determine where spatially and temporally excited species are formed. In this talk we report on spectroscopic studies of the discharge and estimate plasma properties such as temperature and density of excited species and electrons. Furthermore, we report on the effects of pulse polarity as well as anodic streamer discharges on the CO2 conversion efficiency. Finally, we will focus on the effects of vibrational excitation on carbon dioxide reforming efficiency for streamer discharges. Our experimental results will be compared with an accompanying plasma computational model studies.

  2. Optical evidence for a self-propagating molten buried layer in germanium films upon nanosecond laser irradiation

    International Nuclear Information System (INIS)

    Vega, F.; Chaoui, N.; Solis, J.; Armengol, J.; Afonso, C.N.

    2005-01-01

    This work describes the phase transitions occurring at the film-substrate interface of amorphous germanium films upon nanosecond laser-pulse-induced melting of the surface. Films with thickness ranging from 50 to 130 nm deposited on glass substrates were studied. Real-time reflectivity measurements with subnanosecond time resolution performed both at the air-film and film-substrate interfaces were used to obtain both surface and in-depth information of the process. In the thicker films (≥80 nm), the enthalpy released upon solidification of a shallow molten surface layer induces a thin buried liquid layer that self-propagates in-depth towards the film-substrate interface. This buried liquid layer propagates with a threshold velocity of 16±1 m/s and causes, eventually, melting at the film-substrate interface. In the thinnest film (50 nm) there is no evidence of the formation of the buried layer. The presence of the self-propagating buried layer for films thicker than 80 nm at low and intermediate laser fluences is discussed in terms of the thermal gradient in the primary melt front and the heat released upon solidification

  3. Comparative study of ornamental granite cleaning using femtosecond and nanosecond pulsed lasers

    Energy Technology Data Exchange (ETDEWEB)

    Rivas, T., E-mail: trivas@uvigo.es [Dpto. Ingeniería de los Recursos Naturales y Medioambiente. E.T.S. Ingeniería de Minas, Universidad de Vigo, 36200 Vigo Spain (Spain); Lopez, A.J.; Ramil, A. [Centro de Investigaciones Tecnológicas. Campus de Esteiro. Universidad de A Coruña 15403 Ferrol Spain (Spain); Pozo, S. [Dpto. Ingeniería de los Recursos Naturales y Medioambiente. E.T.S. Ingeniería de Minas, Universidad de Vigo, 36200 Vigo Spain (Spain); Fiorucci, M.P. [Centro de Investigaciones Tecnológicas. Campus de Esteiro. Universidad de A Coruña 15403 Ferrol Spain (Spain); Silanes, M.E. López de [Dpto. Ingeniería de los Recursos Naturales y Medioambiente. E.I. Forestales. Universidad de Vigo, Campus Pontevedra. 36005 Pontevedra Spain (Spain); García, A.; Aldana, J. R. Vazquez de; Romero, C.; Moreno, P. [Grupo de Investigación en Microprocesado de Materiales con Laser. Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca Spain (Spain)

    2013-08-01

    Granite has been widely used as a structural and ornamental element in public works and buildings. In damp climates it is almost permanently humid and its exterior surfaces are consequently biologically colonized and blackened We describe a comparative analysis of the performance of two different laser sources in removing biological crusts from granite surfaces: nanosecond Nd:YVO{sub 4} laser (355 nm) and femtosecond Ti:Sapphire laser at its fundamental wavelength (790 nm) and second harmonic (395 nm). The granite surface was analyzed using scanning electron microscopy, attenuated total reflection – Fourier transform infrared spectroscopy and profilometry, in order to assess the degree of cleaning and to characterize possible morphological and chemical changes caused by the laser sources.

  4. Comparative study of ornamental granite cleaning using femtosecond and nanosecond pulsed lasers

    International Nuclear Information System (INIS)

    Rivas, T.; Lopez, A.J.; Ramil, A.; Pozo, S.; Fiorucci, M.P.; Silanes, M.E. López de; García, A.; Aldana, J. R. Vazquez de; Romero, C.; Moreno, P.

    2013-01-01

    Granite has been widely used as a structural and ornamental element in public works and buildings. In damp climates it is almost permanently humid and its exterior surfaces are consequently biologically colonized and blackened We describe a comparative analysis of the performance of two different laser sources in removing biological crusts from granite surfaces: nanosecond Nd:YVO 4 laser (355 nm) and femtosecond Ti:Sapphire laser at its fundamental wavelength (790 nm) and second harmonic (395 nm). The granite surface was analyzed using scanning electron microscopy, attenuated total reflection – Fourier transform infrared spectroscopy and profilometry, in order to assess the degree of cleaning and to characterize possible morphological and chemical changes caused by the laser sources.

  5. Optical diagnosis system for intense electron beam diode plasma

    International Nuclear Information System (INIS)

    Yang Jie; Shu Ting; Zhang Jun; Fan Yuwei; Yang Jianhua; Liu Lie; Yin Yi; Luo Ling

    2012-01-01

    A nanosecond time-resolved imaging platform for diode plasmas diagnostics has been constructed based on the pulsed electron beam accelerator and high speed framing camera (HSFC). The accelerator can provide an electrical pulse with voltages of 200-500 kV, rise-time (from 10% to 90% amplitude) of 25 ns and duration of 110 ns. The diode currents up to kA level can be extracted. The trigger signal for camera was picked up by a water-resistor voltage divider after the main switch of the accelerator, which could avoid the disadvantageous influence of the time jitter caused by the breakdown of the gas gaps. Then the sampled negative electrical pulse was converted into a transistor-transistor logic (TTL) signal (5 V) with rise time of about 1.5 ns and time jitter less than 1 ns via a processor. And this signal was taken as the synchronization time base. According to the working characteristics of the camera, the synchronization scheme relying mainly on electrical pulse delay method supplemented by light signal delay method was determined to make sure that the camera can work synchronously with the light production and transportation from the diode plasma within the time scale of nanosecond. Moreover, shielding and filtering methods were used to restrain the interference on the measurement system from the accelerator. Finally, time resolved 2-D framing images of the diode plasma were acquired. (authors)

  6. Inertial rise of a meniscus on a vertical cylinder

    KAUST Repository

    O’Kiely, Doireann

    2015-03-03

    © © 2015 Cambridge University PressA. We consider the inertia-dominated rise of a meniscus around a vertical circular cylinder. Previous experiments and scaling analysis suggest that the height of the meniscus, h-{m}, grows with the time following the initiation of rise, t, like h-{m}\\\\propto t^{1/2}. This is in contrast to the rise on a vertical plate, which obeys the classic capillary-inertia scaling h-{m}\\\\propto t^{2/3}. We highlight a subtlety in the scaling analysis that yielded h-{m}\\\\propto t^{1/2} and investigate the consequences of this subtlety. We develop a potential flow model of the dynamic problem, which we solve using the finite element method. Our numerical results agree well with previous experiments but suggest that the correct early time behaviour is, in fact, h-{m}\\\\propto t^{2/3}. Furthermore, we show that at intermediate times the dynamic rise of the meniscus is governed by two parameters: the contact angle and the cylinder radius measured relative to the capillary length scale, t^{2/3}. This result allows us to collapse previous experimental results with different cylinder radii (but similar static contact angles) onto a single master curve.

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

    OpenAIRE

    Pai , David ,; Lacoste , Deanna ,; Laux , C.

    2010-01-01

    International audience; In atmospheric pressure air preheated from 300 to 1000 K, the nanosecond repetitively pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determine...

  8. Method for integrating a train of fast, nanosecond wide pulses

    International Nuclear Information System (INIS)

    Rose, C.R.

    1987-01-01

    This paper describes a method used to integrate a train of fast, nanosecond wide pulses. The pulses come from current transformers in a RF LINAC beamline. Because they are ac signals and have no dc component, true mathematical integration would yield zero over the pulse train period or an equally erroneous value because of a dc baseline shift. The circuit used to integrate the pulse train first stretches the pulses to 35 ns FWHM. The signals are then fed into a high-speed, precision rectifier which restores a true dc baseline for the following stage - a fast, gated integrator. The rectifier is linear over 55dB in excess of 25 MHz, and the gated integrator is linear over a 60 dB range with input pulse widths as short as 16 ns. The assembled system is linear over 30 dB with a 6 MHz input signal

  9. Image-rotating cavity designs for improved beam quality in nanosecond optical parametric oscillators

    International Nuclear Information System (INIS)

    Smith, Arlee V.; Bowers, Mark S.

    2001-01-01

    We show by computer simulation that high beam quality can be achieved in high-energy, nanosecond optical parametric oscillators by use of image-rotating resonators. Lateral walk-off between the signal and the idler beams in a nonlinear crystal creates correlations across the beams in the walk off direction, or equivalently, creates a restricted acceptance angle. These correlations can improve the beam quality in the walk-off plane. We show that image rotation or reflection can be used to improve beam quality in both planes. The lateral walk-off can be due to birefringent walk-off in type II mixing or to noncollinear mixing in type I or type II mixing

  10. Precision measurement of sub-nanosecond lifetimes of excited nuclear states using fast-timing coincidences with LaBr3(Ce) detectors

    International Nuclear Information System (INIS)

    Regan, P.H.

    2015-01-01

    Precision measurements of electromagnetic (EM) transition rates enable tests of models of internal nuclear structure. Measurements of transition rates can be used to infer the spin and parity differences between the initial and final discrete nuclear excited states via which the EM transition takes place. This short conference paper reports on developments of detection systems for the identification of discrete energy gamma-ray decays using arrays of halide-scintillation detectors acting in coincidence mode, which can be used to determine electromagnetic transition rates between excited nuclear states in the sub-nanosecond temporal regime. Ongoing development of a new multi-detector LaBr 3 (Ce) array for studies of exotic nuclei produced at the upcoming Facility for Anti-Proton and Ion Research (FAIR) as part of the NUSTAR–DESPEC project are presented, together with initial results from pre-NUSTAR implementations of this array for nuclear structure studies of neutron-rich fission fragment radionuclides at ILL-Grenoble, France and RIBF at RIKEN, Japan. - Highlights: • This paper reports on new detection systems for identification of gamma decays. • It focusses on using arrays of halide-scintillation detectors in coincidence mode. • These can determine lifetimes of nuclear states at the sub-ns level. • Plans for new LaBr3(Ce) arrays for studies of exotic nuclei are presented.

  11. Application of the pulse-rise-time discriminator for background noise decreasing in proportional x-ray counters

    International Nuclear Information System (INIS)

    Goganov, D.A.; Guslina, A.G.; Korolev, V.F.; Lozinskij, B.S.; Sklyankin, V.A.

    1977-01-01

    The intrinsic background of commercial rising edge discriminator - based proportional counters has been measured. The block-diagram of the experimental apparatus comprises the detector to be tested, a charge-sensitive amplifier with an amplitude analyzer, a rising edge discriminator (RED) and a scaling device. The rising edges have been analyzed in the range between 0.2 to 0.7 of the pulse amplitude. The RED threshold has been preset to cut off all the edges longer than those of 55 Fe (to register 87% of the 55 Fe quanta). It has been found that by limiting the amplitude discriminator window to +-20% and using a RED the background of commercial counters can be reduced by about an order

  12. A 'Universal Time' system for ASDEX upgrade

    International Nuclear Information System (INIS)

    Raupp, Gerhard; Cole, R.; Behler, K.; Fitzek, M.; Heimann, P.; Lohs, A.; Lueddecke, K.; Neu, G.; Schacht, J.; Treutterer, W.; Zasche, D.; Zehetbauer, Th.; Zilker, M.

    2003-01-01

    For the new generation of intelligent controllers for plasma diagnostics, discharge control and long-pulse experiment control a new time system supporting steady state real-time operation has been devised. A central unit counts time at nanosecond resolution, covering more than the experiment lifetime. The broadcast time information serves local units to perform application functions such as current time readout, trigger generation and sample time measurement. Time is treated as a precisely measured quantity like other physical quantities. Tagging all detected events and sampled values with measured times as [value; time]-entities facilitates real-time data analysis, steady state protocolling and time-sorted archiving

  13. Electrical and optical characteristics of dielectric-barrier discharge driven by high voltage nanosecond generator

    International Nuclear Information System (INIS)

    Ahmadeev, V.V.; Kost'yuchenko, S.V.; Kudryavtsev, N.N.; Kurkin, G.A.; Vasilyak, L.M.

    1998-01-01

    Electrical and optical characteristics of the dielectric-barrier discharge in the pressure range of 10-400 Torr were investigated experimentally, particular attention being paid to the discharge homogeneity and to the energy dissipation in the discharge volume. The discharge was driven by a high-voltage pulse generator producing nanosecond high-voltage pulses with an amplitude of 20-30 kV. Air, nitrogen, and helium were used as working gases. The discharge was found to be homogeneous within a wide range of gas pressure. A power density of up to 250 mW/cm 3 has been achieved. (J.U.)

  14. Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hu; Noguchi, Jun; Yan, Jiwang [Keio University, Department of Mechanical Engineering, Faculty of Science and Technology, Yokohama (Japan)

    2016-10-15

    Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN. (orig.)

  15. Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass

    Science.gov (United States)

    Huang, Hu; Noguchi, Jun; Yan, Jiwang

    2016-10-01

    Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN.

  16. Nanosecond Level UTC Timing Generation and Stamping in CERN's LHC

    CERN Document Server

    Alvarez, P; Lewis, J; Serrano, J

    2003-01-01

    The General Machine Timing (GMT) at CERN uses an RS-485 multi-drop network through which messages are broadcast by a Central Timing Generator (CTG) module at a rate of 500 kb/s and decoded by many receiver modules in different form factors. For long distance transmission, optical fibers are used. As a result of cabling and capacitive loading of the receivers' inputs, the timing message signal presents an average jitter of 14 ns at any receiver input. For the LHC era, the 500 kb/s rate will be maintained to ensure compatibility with old receivers. However, a special kind of Phase Locked Loop (PLL), involving digital control in a Field Programmable Gate Array (FPGA) and a DAC to control a Voltage Controlled Crystal Oscillator (VCXO), has been developed to generate a 40 MHz square wave at the receiving side which is locked on average to the timing message signal but presents a jitter of less than 1 ns. This 40 MHz signal is locked to UTC because the encoder in the CTG card uses a 40 MHz clock coming from a GPS r...

  17. Nanosecond laser ablated copper superhydrophobic surface with tunable ultrahigh adhesion and its renewability with low temperature annealing

    Science.gov (United States)

    He, An; Liu, Wenwen; Xue, Wei; Yang, Huan; Cao, Yu

    2018-03-01

    Recently, metallic superhydrophobic surfaces with ultrahigh adhesion have got plentiful attention on account of their significance in scientific researches and industrial applications like droplet transport, drug delivery and novel microfluidic devices. However, the long lead time and transience hindered its in-depth development and industrial application. In this work, nanosecond laser ablation was carried out to construct grid of micro-grooves on copper surface, whereafter, by applying fast ethanol assisted low-temperature annealing, we obtained surface with superhydrophobicity and ultrahigh adhesion within hours. And the ultrahigh adhesion force was found tunable by varying the groove spacing. Using ultrasonic cleaning as the simulation of natural wear and tear in service, the renewability of superhydrophobicity was also investigated, and the result shows that the contact angle can rehabilitate promptly by the processing of ethanol assisted low-temperature annealing, which gives a promising fast and cheap circuitous strategy to realize the long wish durable metallic superhydrophobic surfaces in practical applications.

  18. Coal prices rise

    International Nuclear Information System (INIS)

    McLean, A.

    2001-01-01

    Coking and semi hard coking coal price agreements had been reached, but, strangely enough, the reaching of common ground on semi soft coking coal, ultra low volatile coal and thermal coal seemed some way off. More of this phenomenon later, but suffice to say that, traditionally, the semi soft and thermal coal prices have fallen into place as soon as the hard, or prime, coking coal prices have been determined. The rise and rise of the popularity of the ultra low volatile coals has seen demand for this type of coal grow almost exponentially. Perhaps one of the most interesting facets of the coking coal settlements announced to date is that the deals appear almost to have been preordained. The extraordinary thing is that the preordination has been at the prescience of the sellers. Traditionally, coking coal price fixing has been the prerogative of the Japanese Steel Mills (JSM) cartel (Nippon, NKK, Kawasaki, Kobe and Sumitomo) who presented a united front to a somewhat disorganised force of predominantly Australian and Canadian sellers. However, by the time JFY 2001 had come round, the rules of the game had changed

  19. Comparative study of the dissociative ionization of 1,1,1-trichloroethane using nanosecond and femtosecond laser pulses

    CSIR Research Space (South Africa)

    Du Plessis, A

    2010-03-01

    Full Text Available , but different fragmentation patterns. A general trend is that when using femtosecond laser pulses for ionization, the parent molecular ion is observed but not for nanosecond laser ionization. There is also a fundamental interest in laser...-molecule interactions at the high intensities available from femtosecond lasers [12,13]. These papers describe the multiphoton ionization mechanisms termed ladder climbing and ladder switching, which explain the presence of parent molecular ion in ultrashort pulse...

  20. RADIOACTIVELY POWERED RISING LIGHT CURVES OF TYPE Ia SUPERNOVAE

    International Nuclear Information System (INIS)

    Piro, Anthony L.

    2012-01-01

    The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first ≈0.5-4 days. In addition, studies of the composite light curves formed from stacking together many Type Ia supernovae (SNe Ia) have found similar power-law indices for the rise, but may also show some dispersion that may indicate diversity. I explore what range of power-law rises are possible due to the presence of radioactive material near the surface of the exploding white dwarf (WD). I summarize what constraints such a model places on the structure of the progenitor and the distribution and velocity of ejecta. My main conclusion is that for the inferred explosion time for SN 2011fe, its rise requires an increasing mass fraction X 56 ≈ (4-6) × 10 –2 of 56 Ni distributed between a depth of ≈10 –2 and 0.3 M ☉ below the WD's surface. Radioactive elements this shallow are not found in simulations of a single C/O detonation. Scenarios that may produce this material include helium-shell burning during a double-detonation ignition, a gravitationally confined detonation, and a subset of deflagration to detonation transition models. In general, the power-law rise can differ from quadratic depending on the details of the velocity, density, and radioactive deposition gradients in a given event. Therefore, comparisons of this work with observed bolometric rises of SNe Ia would place strong constraints on the properties of the shallow outer layers, providing important clues for identifying the elusive progenitors of SNe Ia.

  1. Nanosecond and femtosecond mass spectroscopic analysis of a molecular beam produced by the spray-jet technique

    International Nuclear Information System (INIS)

    Yamada, Toshiki; Shinohara, Hidenori; Kamikado, Toshiya; Okuno, Yoshishige; Suzuki, Hitoshi; Mashiko, Shinro; Yokoyama, Shiyoshi

    2008-01-01

    The spray-jet molecular beam apparatus enabled us to produce a molecular beam of non-volatile molecules under high vacuum from a sprayed mist of sample solutions. The apparatus has been used in spectroscopic studies and as a means of molecular beam deposition. We analyzed the molecular beam, consisting of non-volatile, solvent, and carrier-gas molecules, by using femtosecond- and nanosecond- laser mass spectroscopy. The information thus obtained provided insight into the molecular beam produced by the spray-jet technique

  2. Redox reaction studies by nanosecond pulse radiolysis

    International Nuclear Information System (INIS)

    Moorthy, P.N.

    1979-01-01

    Free radicals are formed as intermediates in many chemical and biochemical reactions. An important type of reaction which they can undergo is a one electron or redox process. The direction and rate of such electron transfer reactions is governed by the relative redox potentials of the participating species. Because of the generally short lived nature of free radicals, evaluation of their redox potentials poses a number of problems. Two techniques are described for the experimental determination of the redox potentials of short lived species generated by either a nanosecond electron pulse or laser flash. In the first method, redox titration of the short lived species with stable molecules of known redox potential is carried out, employing the technique of fast kinetic spectrophotometry. Conversely, by the same method it is also possible to evaluate the one electron redox potentials of stable molecules by redox titration with free radicals of known redox potential produced as above. In the second method, electrochemical reduction or oxidation of the short lived species at an appropriate electrode (generally a mercury drop) is carried out at different fixed potentials, and the redox potential evaluated from the current-potential curves (polarograms). Full description of the experimental set up and theoretical considerations for interpretation of the raw data are given. The relative merits of the two methods and their practical applicability are discussed. (auth.)

  3. Nanosecond laser ablation and deposition of silver, copper, zinc and tin

    DEFF Research Database (Denmark)

    Cazzaniga, Andrea Carlo; Ettlinger, Rebecca Bolt; Canulescu, Stela

    2014-01-01

    Nanosecond pulsed laser deposition of different metals (Ag, Cu, Sn, Zn) has been studied in high vacuum at a laser wavelength of 355 nm and pulse length of 6 ns. The deposition rate is roughly similar for Sn, Cu and Ag, which have comparable cohesive energies, and much higher for the deposition...... of Zn which has a low cohesive energy. The deposition rate for all metals is strongly correlated with the total ablation yield, i.e., the total mass ablated per pulse, reported in the literature except for Sn, for which the deposition rate is low, but the total ablation yield is high. This may...... be explained by the continuous erosion by nanoparticles during deposition of the Sn films which appear to have a much rougher surface than those of the other metals studied in the present work....

  4. Two modes of cell death caused by exposure to nanosecond pulsed electric field.

    Directory of Open Access Journals (Sweden)

    Olga N Pakhomova

    Full Text Available High-amplitude electric pulses of nanosecond duration, also known as nanosecond pulsed electric field (nsPEF, are a novel modality with promising applications for cell stimulation and tissue ablation. However, key mechanisms responsible for the cytotoxicity of nsPEF have not been established. We show that the principal cause of cell death induced by 60- or 300-ns pulses in U937 cells is the loss of the plasma membrane integrity ("nanoelectroporation", leading to water uptake, cell swelling, and eventual membrane rupture. Most of this early necrotic death occurs within 1-2 hr after nsPEF exposure. The uptake of water is driven by the presence of pore-impermeable solutes inside the cell, and can be counterbalanced by the presence of a pore-impermeable solute such as sucrose in the medium. Sucrose blocks swelling and prevents the early necrotic death; however the long-term cell survival (24 and 48 hr does not significantly change. Cells protected with sucrose demonstrate higher incidence of the delayed death (6-24 hr post nsPEF. These cells are more often positive for the uptake of an early apoptotic marker dye YO-PRO-1 while remaining impermeable to propidium iodide. Instead of swelling, these cells often develop apoptotic fragmentation of the cytoplasm. Caspase 3/7 activity increases already in 1 hr after nsPEF and poly-ADP ribose polymerase (PARP cleavage is detected in 2 hr. Staurosporin-treated positive control cells develop these apoptotic signs only in 3 and 4 hr, respectively. We conclude that nsPEF exposure triggers both necrotic and apoptotic pathways. The early necrotic death prevails under standard cell culture conditions, but cells rescued from the necrosis nonetheless die later on by apoptosis. The balance between the two modes of cell death can be controlled by enabling or blocking cell swelling.

  5. Technological features of installation of transformable low-rise buildings from sandwich panels

    Directory of Open Access Journals (Sweden)

    Pleshivtsev Aleksandr Aleksandrovich

    2018-04-01

    Full Text Available Subject of research: organizational and technological solutions are considered in the construction of transformable low-rise residential buildings using sandwich panels. Aims: rational choice of organizational and technological solutions for the rhythmic construction of the underground and above-ground part of the transformable low-rise buildings in order to reduce labor costs and construction time. Materials and methods: methods of computer modeling of the technological processes are used to determine the duration of the construction of the low-rise buildings. Results: rational methods for erecting a complex of transformable low-rise buildings are defined, parameters of technological processes are established, an analysis of technological operations is provided for the construction of transformable low-rise residential buildings using sandwich panels. Conclusions: now organizational and technological solutions for the construction of transformable low-rise residential buildings with the use of sandwich panels reduce labour costs, increase the construction pace and as well as the using of improved technological processes in the construction of such buildings leads to a reduction in construction time.

  6. Development of the bubble rise model in RELAP-UK

    International Nuclear Information System (INIS)

    Holmes, J.A.

    1977-11-01

    Several improvements have been made to the 'bubble rise calculation' in the code RELAP-UK, which models the separation of the steam and water phases within specified volumes of the coolant circuit. The bubble rise velocity and the bubble density gradient parameter are no longer necessarily user-defined constants, as the code can calculate their values at each time step according to the local fluid conditions. In particular, the calculation of the bubble rise velocity is consistent with the RELAP-UK drift flux correlation. It is now possible to represent a vertical column by a stack of vertically-adjacent bubble-rise volumes. Any mixture level existing within the column can freely pass between the volumes in the stack. The facilities are demonstrated in this paper by a simple computational example. (author)

  7. Short Lived Climate Pollutants cause a Long Lived Effect on Sea-level Rise: Analyzing climate metrics for sea-level rise

    Science.gov (United States)

    Sterner, E.; Johansson, D. J.

    2013-12-01

    Climate change depends on the increase of several different atmospheric pollutants. While long term global warming will be determined mainly by carbon dioxide, warming in the next few decades will depend to a large extent on short lived climate pollutants (SLCP). Reducing emissions of SLCPs could contribute to lower the global mean surface temperature by 0.5 °C already by 2050 (Shindell et al. 2012). Furthermore, the warming effect of one of the most potent SLCPs, black carbon (BC), may have been underestimated in the past. Bond et al. (2013) presents a new best estimate of the total BC radiative forcing (RF) of 1.1 W/m2 (90 % uncertainty bounds of 0.17 to 2.1 W/m2) since the beginning of the industrial era. BC is however never emitted alone and cooling aerosols from the same sources offset a majority of this RF. In the wake of calls for mitigation of SLCPs it is important to study other aspects of the climate effect of SLCPs. One key impact of climate change is sea-level rise (SLR). In a recent study, the effect of SLCP mitigation scenarios on SLR is examined. Hu et al (2013) find a substantial effect on SLR from mitigating SLCPs sharply, reducing SLR by 22-42% by 2100. We choose a different approach focusing on emission pulses and analyse a metric based on sea level rise so as to further enlighten the SLR consequences of SLCPs. We want in particular to understand the time dynamics of SLR impacts caused by SLCPs compared to other greenhouse gases. The most commonly used physical based metrics are GWP and GTP. We propose and evaluate an additional metric: The global sea-level rise potential (GSP). The GSP is defined as the sea level rise after a time horizon caused by an emissions pulse of a forcer to the sea level rise after a time horizon caused by an emissions pulse of a CO2. GSP is evaluated and compared to GWP and GTP using a set of climate forcers chosen to cover the whole scale of atmospheric perturbation life times (BC, CH4, N2O, CO2 and SF6). The study

  8. Studies of nanosecond pulse surface ionization wave discharges over solid and liquid dielectric surfaces

    International Nuclear Information System (INIS)

    Petrishchev, Vitaly; Leonov, Sergey; Adamovich, Igor V

    2014-01-01

    Surface ionization wave discharges generated by high-voltage nanosecond pulses, propagating over a planar quartz surface and over liquid surfaces (distilled water and 1-butanol) have been studied in a rectangular cross section test cell. The discharge was initiated using a custom-made, alternating polarity, high-voltage nanosecond pulse plasma generator, operated at a pulse repetition rate of 100–500 Hz, with a pulse peak voltage and current of 10–15 kV and 7–20 A, respectively, a pulse FWHM of ∼100 ns, and a coupled pulse energy of 2–9 mJ/pulse. Wave speed was measured using a capacitive probe. ICCD camera images demonstrated that the ionization wave propagated predominantly over the quartz wall or over the liquid surface adjacent to the grounded waveguide placed along the bottom wall of the test cell. Under all experimental conditions tested, the surface plasma ‘sheet’ was diffuse and fairly uniform, both for positive and negative polarities. The parameters of ionization wave discharge propagating over distilled water and 1-butanol surfaces were close to those of the discharge over a quartz wall. No perturbation of the liquid surface by the discharge was detected. In most cases, the positive polarity surface ionization wave propagated at a higher speed and over a longer distance compared to the negative polarity wave. For all three sets of experiments (surface ionization wave discharge over quartz, water and 1-butanol), wave speed and travel distance decreased with pressure. Diffuse, highly reproducible surface ionization wave discharge was also observed over the liquid butanol–saturated butanol vapor interface, as well as over the distilled water–saturated water vapor interface, without buffer gas flow. No significant difference was detected between surface ionization discharges sustained using single-polarity (positive or negative), or alternating polarity high-voltage pulses. Plasma emission images yielded preliminary evidence of charge

  9. Write/erase time of nanoseconds in quantum dot based memory structures

    International Nuclear Information System (INIS)

    Nowozin, Tobias; Marent, Andreas; Geller, Martin; Bimberg, Dieter

    2008-01-01

    We have developed a novel charge-storage memory concept based on III-V semiconductor quantum dots (QDs) which has a number of fundamental advantages over conventional Si/SiO 2 floating gate memories (Flash): material-tunable and voltage-tunable barriers for improved intrinsic speed and/or storage time and high endurance. To investigate the potential of this new memory concept we have determined intrinsic write/erase times in memory structures based on InAs/GaAs and GaSb/GaAs QDs using capacitance-voltage spectroscopy. We measured a write time below 15 ns independent of the localization energy (i.e. the storage time) of the QDs. This write time is more than three orders of magnitude faster than in a Flash cell and already below the write time of a dynamic random access memory (DRAM). The erase time was determined to be 42 ns for InAs/GaAs QDs and 1.5 ms for GaSb/GaAs QDs for applied electric fields of 166 kV/cm and 206 kV/cm, respectively. From these results we derive an erase time of 1 ns in GaSb QDs for an electric field of 330 kV/cm

  10. Rising tides, rising gates: The complex ecogeomorphic response of coastal wetlands to sea-level rise and human interventions

    Science.gov (United States)

    Sandi, Steven G.; Rodríguez, José F.; Saintilan, Neil; Riccardi, Gerardo; Saco, Patricia M.

    2018-04-01

    Coastal wetlands are vulnerable to submergence due to sea-level rise, as shown by predictions of up to 80% of global wetland loss by the end of the century. Coastal wetlands with mixed mangrove-saltmarsh vegetation are particularly vulnerable because sea-level rise can promote mangrove encroachment on saltmarsh, reducing overall wetland biodiversity. Here we use an ecogeomorphic framework that incorporates hydrodynamic effects, mangrove-saltmarsh dynamics, and soil accretion processes to assess the effects of control structures on wetland evolution. Migration and accretion patterns of mangrove and saltmarsh are heavily dependent on topography and control structures. We find that current management practices that incorporate a fixed gate for the control of mangrove encroachment are useful initially, but soon become ineffective due to sea-level rise. Raising the gate, to counteract the effects of sea level rise and promote suitable hydrodynamic conditions, excludes mangrove and maintains saltmarsh over the entire simulation period of 100 years

  11. Electric field measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond electric field induced second harmonic generation

    Science.gov (United States)

    Goldberg, Benjamin M.; Chng, Tat Loon; Dogariu, Arthur; Miles, Richard B.

    2018-02-01

    We present an optical electric field measurement method for use in high pressure plasma discharges. The method is based upon the field induced second harmonic generation technique and can be used for localized electric field measurements with sub-nanosecond resolution in any gaseous species. When an external electric field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the electric field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the electric field is strong enough to exceed the breakdown threshold, the measured field was shown to exceed the anticipated voltage to gap ratio which is taken as an indication of the ionization wave front as it sweeps through the plasma volume.

  12. Fast gas heating and radial distribution of active species in nanosecond capillary discharge in pure nitrogen and N2:O2 mixtures

    Science.gov (United States)

    Lepikhin, N. D.; Popov, N. A.; Starikovskaia, S. M.

    2018-05-01

    Fast gas heating is studied experimentally and numerically using pulsed nanosecond capillary discharge in pure nitrogen and N2:O2 mixtures under the conditions of high specific deposited energy (up to 1 eV/molecule) and high reduced electric fields (100–300 Td). Deposited energy, electric field and gas temperature are measured as functions of time. The radial distribution of active species is analyzed experimentally. The roles of processes involving {{{N}}}2({{B}}) ={{{N}}}2({{{B}}}3{{{\\Pi }}}{{g}},{{{W}}}3{{{Δ }}}{{u}},{{B}}{{\\prime} }3{{{Σ }}}{{u}}-), {{{N}}}2({{{A}}}3{{{Σ }}}{{u}}+) and N(2D) excited nitrogen species leading to heat release are analyzed using numerical modeling in the framework of 1D axial approximation.

  13. Wide-field time-correlated single photon counting (TCSPC) microscopy with time resolution below the frame exposure time

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M. [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Petrášek, Zdeněk [Max Planck Institute of Biochemistry, Department of Cellular and Molecular Biophysics, Am Klopferspitz 18, D-82152 Martinsried (Germany); Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom)

    2015-07-01

    Fast frame rate CMOS cameras in combination with photon counting intensifiers can be used for fluorescence imaging with single photon sensitivity at kHz frame rates. We show here how the phosphor decay of the image intensifier can be exploited for accurate timing of photon arrival well below the camera exposure time. This is achieved by taking ratios of the intensity of the photon events in two subsequent frames, and effectively allows wide-field TCSPC. This technique was used for measuring decays of ruthenium compound Ru(dpp) with lifetimes as low as 1 μs with 18.5 μs frame exposure time, including in living HeLa cells, using around 0.1 μW excitation power. We speculate that by using an image intensifier with a faster phosphor decay to match a higher camera frame rate, photon arrival time measurements on the nanosecond time scale could well be possible.

  14. Time-resolved x-ray line emission studies of thermal transport in multiple beam uv-irradiated targets

    International Nuclear Information System (INIS)

    Jaanimagi, P.A.; Henke, B.L.; Delettrez, J.; Richardson, M.C.

    1984-01-01

    Thermal transport in spherical targets irradiated with multiple, nanosecond duration laser beams, has been a topic of much discussion recently. Different inferences on the level of thermal flux inhibition have been drawn from plasma velocity and x-ray spectroscopic diagnostics. We present new measurements of thermal transport on spherical targets made through time-resolved x-ray spectroscopic measurements of the progress of the ablation surface through thin layers of material on the surface of the target. These measurements, made with 6 and 12 uv (351 nm) nanosecond beams from OMEGA, will be compared to previous thermal transport measurements. Transparencies of the conference presentation are given

  15. Dynamics of the plume produced by nanosecond ultraviolet laser ablation of metals

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen; Lunney, J.G.

    2003-01-01

    The dynamics of the ablation plume of a partially ionized plasma produced by a nanosecond UV laser with different irradiation spot geometries has been explored. We have used an ensemble of quartz crystal microbalances to make the first systematic and quantitative study of how the shape of the plume...... varies as the aspect ratio (b/a) of the elliptical laser spot is varied by about a factor of ten. The flip-over effect can be described by the adiabatic expansion model of Anisimov using a value of the adiabatic constant of about gamma = 1.4. We have also studied the forward peaking of the ablation plume...... for a large number of metals at the same laser fluence. Contrary to earlier reports, we find that the more refractory metals have the broader angular distributions....

  16. Assessment of Temperature Rise and Time of Alveolar Ridge Splitting by Means of Er:YAG Laser, Piezosurgery, and Surgical Saw: An Ex Vivo Study.

    Science.gov (United States)

    Matys, Jacek; Flieger, Rafał; Dominiak, Marzena

    2016-01-01

    The most common adverse effect after bone cutting is a thermal damage. The aim of our study was to evaluate the bone temperature rise during an alveolar ridge splitting, rating the time needed to perform this procedure and the time to raise the temperature of a bone by 10°C, as well as to evaluate the bone carbonization occurrence. The research included 60 mandibles ( n = 60) of adult pigs, divided into 4 groups ( n = 15). Two vertical and one horizontal cut have been done in an alveolar ridge using Er:YAG laser with set power of 200 mJ (G1), 400 mJ (G2), piezosurgery unit (G3), and a saw (G4). The temperature was measured by K-type thermocouple. The highest temperature gradient was noted for piezosurgery on the buccal and lingual side of mandible. The temperature rises on the bone surface along with the increase of laser power. The lower time needed to perform ridge splitting was measured for a saw, piezosurgery, and Er:YAG laser with power of 400 mJ and 200 mJ, respectively. The temperature rise measured on the bone over 10°C and bone carbonization occurrence was not reported in all study groups. Piezosurgery, Er:YAG laser (200 mJ and 400 mJ), and surgical saw are useful and safe tools in ridge splitting surgery.

  17. Assessment of Temperature Rise and Time of Alveolar Ridge Splitting by Means of Er:YAG Laser, Piezosurgery, and Surgical Saw: An Ex Vivo Study

    Directory of Open Access Journals (Sweden)

    Jacek Matys

    2016-01-01

    Full Text Available The most common adverse effect after bone cutting is a thermal damage. The aim of our study was to evaluate the bone temperature rise during an alveolar ridge splitting, rating the time needed to perform this procedure and the time to raise the temperature of a bone by 10°C, as well as to evaluate the bone carbonization occurrence. The research included 60 mandibles (n=60 of adult pigs, divided into 4 groups (n=15. Two vertical and one horizontal cut have been done in an alveolar ridge using Er:YAG laser with set power of 200 mJ (G1, 400 mJ (G2, piezosurgery unit (G3, and a saw (G4. The temperature was measured by K-type thermocouple. The highest temperature gradient was noted for piezosurgery on the buccal and lingual side of mandible. The temperature rises on the bone surface along with the increase of laser power. The lower time needed to perform ridge splitting was measured for a saw, piezosurgery, and Er:YAG laser with power of 400 mJ and 200 mJ, respectively. The temperature rise measured on the bone over 10°C and bone carbonization occurrence was not reported in all study groups. Piezosurgery, Er:YAG laser (200 mJ and 400 mJ, and surgical saw are useful and safe tools in ridge splitting surgery.

  18. Raising the avermectins production in Streptomyces avermitilis by utilizing nanosecond pulsed electric fields (nsPEFs)

    Science.gov (United States)

    Guo, Jinsong; Ma, Ruonan; Su, Bo; Li, Yinglong; Zhang, Jue; Fang, Jing

    2016-05-01

    Avermectins, a group of anthelmintic and insecticidal agents produced from Streptomyces avermitilis, are widely used in agricultural, veterinary, and medical fields. This study presents the first report on the potential of using nanosecond pulsed electric fields (nsPEFs) to improve avermectin production in S. avermitilis. The results of colony forming units showed that 20 pulses of nsPEFs at 10 kV/cm and 20 kV/cm had a significant effect on proliferation, while 100 pulses of nsPEFs at 30 kV/cm exhibited an obvious effect on inhibition of agents. Ultraviolet spectrophotometry assay revealed that 20 pulses of nsPEFs at 15 kV/cm increased avermectin production by 42% and reduced the time for reaching a plateau in fermentation process from 7 days to 5 days. In addition, the decreased oxidation reduction potential (ORP) and increased temperature of nsPEFs-treated liquid were evidenced to be closely associated with the improved cell growth and fermentation efficiency of avermectins in S. avermitilis. More importantly, the real-time RT-PCR analysis showed that nsPEFs could remarkably enhance the expression of aveR and malE in S. avermitilis during fermentation, which are positive regulator for avermectin biosynthesis. Therefore, the nsPEFs technology presents an alternative strategy to be developed to increase avermectin output in fermentation industry.

  19. Projecting Future Sea Level Rise for Water Resources Planning in California

    Science.gov (United States)

    Anderson, J.; Kao, K.; Chung, F.

    2008-12-01

    Sea level rise is one of the major concerns for the management of California's water resources. Higher water levels and salinity intrusion into the Sacramento-San Joaquin Delta could affect water supplies, water quality, levee stability, and aquatic and terrestrial flora and fauna species and their habitat. Over the 20th century, sea levels near San Francisco Bay increased by over 0.6ft. Some tidal gauge and satellite data indicate that rates of sea level rise are accelerating. Sea levels are expected to continue to rise due to increasing air temperatures causing thermal expansion of the ocean and melting of land-based ice such as ice on Greenland and in southeastern Alaska. For water planners, two related questions are raised on the uncertainty of future sea levels. First, what is the expected sea level at a specific point in time in the future, e.g., what is the expected sea level in 2050? Second, what is the expected point of time in the future when sea levels will exceed a certain height, e.g., what is the expected range of time when the sea level rises by one foot? To address these two types of questions, two factors are considered: (1) long term sea level rise trend, and (2) local extreme sea level fluctuations. A two-step approach will be used to develop sea level rise projection guidelines for decision making that takes both of these factors into account. The first step is developing global sea level rise probability distributions for the long term trends. The second step will extend the approach to take into account the effects of local astronomical tides, changes in atmospheric pressure, wind stress, floods, and the El Niño/Southern Oscillation. In this paper, the development of the first step approach is presented. To project the long term sea level rise trend, one option is to extend the current rate of sea level rise into the future. However, since recent data indicate rates of sea level rise are accelerating, methods for estimating sea level rise

  20. SEISMIC Analysis of high-rise buildings with composite metal damper

    Directory of Open Access Journals (Sweden)

    Chen Ruixue

    2015-01-01

    Full Text Available This paper mainly studies on the mechanical characteristics and application effect of composite metal damper in the high-rise buildings via the numerical simulation analysis. The research adopts the elastic and elastic-plastic dynamic approach and the displacement time history response and damper energy dissipation capacity and so on of the high-rise building are compared and analyzed before and after installation. The analysis found that the energy dissipation characteristic of metallic dampers is good. High-rise building story drift significantly is reduced and the extent of damage of the walls and coupling beams is decreased, achieved a good energy dissipation effect. Composite metal damper can effectively and economically improve the seismic performance of high-rise buildings, meet the requirement of the 3-level design for seismic resistance. The result has certain reference significance for the application of metallic damper in the high-rise buildings.

  1. Ablation of (GeS2)0.3(Sb2S3)0.7 glass with an ultra-violet nano-second laser

    International Nuclear Information System (INIS)

    Knotek, P.; Navesnik, J.; Cernohorsky, T.; Kincl, M.; Vlcek, M.; Tichy, L.

    2015-01-01

    Highlights: • The interaction of (GeS 2 ) 0.3 (Sb 2 S 3 ) 0.7 bulk glass and film with UV nanosecond laser. • Ablation process, topography of crater and structure of the material were studied. • Ablation threshold fluencies changed with the spot diameter and number of pulses. • The photo-thermal expansion of the material occurred for low laser fluency. • Laser direct writing process applicable for fabrication of passive optical elements. - Abstract: The results of an experimental study of the laser ablation of bulk and thin films of a GeSbS chalcogenide glass using UV nanosecond pulses are reported. The response of the samples to illumination conditions was studied through the use of atomic force spectroscopy, digital holographic microscopy, Raman scattering and scanning electron microscopy. The multi-pulse ablation thresholds were determined for both the bulk and thin film samples for varying number of pulses and illuminated spot diameter. The possible application of direct laser writing into the bulk and thin films of this material is presented

  2. Microfossil measures of rapid sea-level rise: Timing of response of two microfossil groups to a sudden tidal-flooding experiment in Cascadia

    Science.gov (United States)

    Horton, B.P.; Milker, Yvonne; Dura, T.; Wang, Kelin; Bridgeland, W.T.; Brophy, Laura S.; Ewald, M.; Khan, Nicole; Engelhart, S.E.; Nelson, Alan R.; Witter, Robert C.

    2017-01-01

    Comparisons of pre-earthquake and post-earthquake microfossils in tidal sequences are accurate means to measure coastal subsidence during past subduction earthquakes, but the amount of subsidence is uncertain, because the response times of fossil taxa to coseismic relative sea-level (RSL) rise are unknown. We measured the response of diatoms and foraminifera to restoration of a salt marsh in southern Oregon, USA. Tidal flooding following dike removal caused an RSL rise of ∼1 m, as might occur by coseismic subsidence during momentum magnitude (Mw) 8.1–8.8 earthquakes on this section of the Cascadia subduction zone. Less than two weeks after dike removal, diatoms colonized low marsh and tidal flats in large numbers, showing that they can record seismically induced subsidence soon after earthquakes. In contrast, low-marsh foraminifera took at least 11 months to appear in sizeable numbers. Where subsidence measured with diatoms and foraminifera differs, their different response times may provide an estimate of postseismic vertical deformation in the months following past megathrust earthquakes.

  3. Is thermodynamic irreversibility a consequence of the expansion of the Universe?

    Science.gov (United States)

    Osváth, Szabolcs

    2018-02-01

    This paper explains thermodynamic irreversibility by applying the expansion of the Universe to thermodynamic systems. The effect of metric expansion is immeasurably small on shorter scales than intergalactic distances. Multi-particle systems, however, are chaotic, and amplify any small disturbance exponentially. Metric expansion gives rise to time-asymmetric behaviour in thermodynamic systems in a short time (few nanoseconds in air, few ten picoseconds in water). In contrast to existing publications, this paper explains without any additional assumptions the rise of thermodynamic irreversibility from the underlying reversible mechanics of particles. Calculations for the special case which assumes FLRW metric, slow motions (v ≪ c) and approximates space locally by Euclidean space show that metric expansion causes entropy increase in isolated systems. The rise of time-asymmetry, however, is not affected by these assumptions. Any influence of the expansion of the Universe on the local metric causes a coupling between local mechanics and evolution of the Universe.

  4. Technological innovations and the rise of social inequalities in health.

    Science.gov (United States)

    Weiss, Daniel; Eikemo, Terje Andreas

    2017-11-01

    Social inequalities in health have been categorised as a human-rights issue that requires action. Unfortunately, these inequalities are on the rise in many countries, including welfare states. Various theories have been offered to explain the persistence (and rise) of these inequalities over time, including the social determinants of health and fundamental cause theory. Interestingly, the rise of modern social inequalities in health has come at a time of great technological innovation. This article addresses whether these technological innovations are significantly influencing the persistence of modern social inequalities in health. A theoretical argument is offered for this potential connection and is discussed alongside the typical social determinants of health perspective and the increasingly popular fundamental cause perspective. This is followed by a proposed research agenda for further investigation of the potential role that technological innovations may play in influencing social inequalities in health.

  5. Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

    Science.gov (United States)

    Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

    2015-02-01

    We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz.

  6. Nanosecond field emitted and photo-field emitted current pulses from ZrC tips

    International Nuclear Information System (INIS)

    Ganter, R.; Bakker, R.J.; Gough, C.; Paraliev, M.; Pedrozzi, M.; Le Pimpec, F.; Rivkin, L.; Wrulich, A.

    2006-01-01

    In order to find electron sources with low thermal emittance, cathodes based on single tip field emitter are investigated. Maximum peak current, measured from single tip in ZrC with a typical apex radius around 1 μm, are presented. Voltage pulses of 2 ns duration and up to 50 kV amplitude lead to field emission current up to 470 mA from one ZrC tip. Combination of high applied electric field with laser illumination gives the possibility to modulate the emission with laser pulses. Nanoseconds current pulses have been emitted with laser pulses at 1064 nm illuminating a ZrC tip under high-DC electric field. The dependence of photo-field emitted current with the applied voltage can be explained by the Schottky effect

  7. Nanosecond field emitted and photo-field emitted current pulses from ZrC tips

    Energy Technology Data Exchange (ETDEWEB)

    Ganter, R. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland)]. E-mail: romain.ganter@psi.ch; Bakker, R.J. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Gough, C. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Paraliev, M. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Pedrozzi, M. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Le Pimpec, F. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Rivkin, L. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Wrulich, A. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland)

    2006-09-15

    In order to find electron sources with low thermal emittance, cathodes based on single tip field emitter are investigated. Maximum peak current, measured from single tip in ZrC with a typical apex radius around 1 {mu}m, are presented. Voltage pulses of 2 ns duration and up to 50 kV amplitude lead to field emission current up to 470 mA from one ZrC tip. Combination of high applied electric field with laser illumination gives the possibility to modulate the emission with laser pulses. Nanoseconds current pulses have been emitted with laser pulses at 1064 nm illuminating a ZrC tip under high-DC electric field. The dependence of photo-field emitted current with the applied voltage can be explained by the Schottky effect.

  8. The 1988 coal outlook: steadily rising consumption

    Energy Technology Data Exchange (ETDEWEB)

    Soras, C.G.; Stodden, J.R.

    1987-12-01

    Total coal use - domestic and foreign - will reach 910 million tons in 1988, an expansion of 1.3% from an estimated 898 million tons in 1987. The overall rise in consumption will add to inventory needs. Moreover, lower interest rates cut effective carrying costs and further encourage the holding of coal stocks by users. The results will be a gain in inventories of 3.5 tons by the end of 1988. As a result of all these factors, coal production is anticipated to rise by 11.6 million tons, or 1.2%, which projects firm markets in a time of relatively soft economic conditions in the USA. 2 tabs.

  9. Synchronized and configurable source of electrical pulses for x-ray pump-probe experiments

    International Nuclear Information System (INIS)

    Strachan, J. P.; Chembrolu, V.; Yu, X. W.; Tyliszczak, T.; Acremann, Y.

    2007-01-01

    A method is described for the generation of software tunable patterns of nanosecond electrical pulses. The bipolar, high repetition rate (up to 250 MHz), fast rise time (<30 ps), square pulses are suitable for applications such as the excitation sequence in dynamic pump-probe experiments. Synchronization with the time structure of a synchrotron facility is possible as well as fine control of the relative delay in steps of 10 ps. The pulse generator described here is used to excite magnetic nanostructures with current pulses. Having an excitation system which can match the high repetition rate of a synchrotron allows for utilization of the full x-ray flux and is needed in experiments which require a large photon flux. The fast rise times allow for picosecond time resolution in pump-probe experiments. All pulse pattern parameters are configurable by software

  10. Statistics of EMIC Rising Tones Observed by the Van Allen Probes

    Science.gov (United States)

    Sigsbee, K. M.; Kletzing, C.; Smith, C. W.; Santolik, O.

    2017-12-01

    We will present results from an ongoing statistical study of electromagnetic ion cyclotron (EMIC) wave rising tones observed by the Van Allen Probes. Using data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) fluxgate magnetometer, we have identified orbits by both Van Allen Probes with EMIC wave events from the start of the mission in fall 2012 through fall 2016. Orbits with EMIC wave events were further examined for evidence of rising tones. Most EMIC wave rising tones were found during H+ band EMIC wave events. In Fourier time-frequency power spectrograms of the fluxgate magnetometer data, H+ band rising tones generally took the form of triggered emission type events, where the discrete rising tone structures rapidly rise in frequency out of the main band of observed H+ EMIC waves. A smaller percentage of EMIC wave rising tone events were found in the He+ band, where rising tones may appear as discrete structures with a positive slope embedded within the main band of observed He+ EMIC waves, similar in appearance to whistler-mode chorus elements. Understanding the occurrence rate and properties of rising tone EMIC waves will provide observational context for theoretical studies indicating that EMIC waves exhibiting non-linear behavior, such as rising tones, may be more effective at scattering radiation belt electrons than ordinary EMIC waves.

  11. Chair rise capacity and associated factors in older home-care clients.

    Science.gov (United States)

    Tiihonen, Miia; Hartikainen, Sirpa; Nykänen, Irma

    2017-07-01

    The aim of this study was to investigate the ability of older home-care clients to perform the five times chair rise test and associated personal characteristics, nutritional status and functioning. The study sample included 267 home-care clients aged ≥75 years living in Eastern and Central Finland. The home-care clients were interviewed at home by home-care nurses, nutritionists and pharmacists. The collected data contained sociodemographic factors, functional ability (Barthel Index, IADL), cognitive functioning (MMSE), nutritional status (MNA), depressive symptoms (GDS-15), medical diagnoses and drug use. The primary outcome was the ability to perform the five times chair rise test. Fifty-one per cent ( n=135) of the home-care clients were unable to complete the five times chair rise test. Twenty-three per cent ( n=64) of the home-care clients had good chair rise capacity (≤17 seconds). In a multivariate logistic regression analysis, fewer years of education (odds ratio [OR] = 1.11, 95% confidence interval [CI] 1.04-1.18), lower ADL (OR = 1.54, 95% CI 1.34-1.78) and low MNA scores (OR = 1.12, 95% CI 1.04-1.20) and a higher number of co-morbidities (OR = 1.21, 95% CI 1.02-1.43) were associated with inability to complete the five times chair rise test. Poor functional mobility, which was associated with less education, a high number of co-morbidities and poor nutritional status, was common among older home-care clients. To maintain and to prevent further decline in functional mobility, physical training and nutritional services are needed. (NutOrMed, ClinicalTrials.gov Identifier: NCT02214758).

  12. Large Topographic Rises on Venus: Implications for Mantle Upwelling

    Science.gov (United States)

    Stofan, Ellen R.; Smrekar, Suzanne E.; Bindschandler, Duane L.; Senske, David A.

    1995-01-01

    Topographic rises on Venus have been identified that are interpreted to be the surface manifestation of mantle upwellings. These features are classified into groups based on their dominant morphology. Atla and Beta Regiones are classified as rift-dominated, Dione, western Eistla, Bell, and Imdr Regiones as volcano-dominated, and Themis, eastern Eistla, and central Eistla Regiones as corona-dominated. At several topographic rises, geologic indicators were identified that may provide evidence of uplifted topography (e.g., volcanic flow features trending upslope). We assessed the minimum contribution of volcanic construction to the topography of each rise, which in general represents less than 5% of the volume of the rise, similar to the volumes of edifices at terrestrial hotspot swells. The total melt volume at each rise is approximated to be 10(exp 4) - 10(exp 6) cu km. The variations in morphology, topography, and gravity signatures at topographic rises are not interpreted to indicate variations in stage of evolution of a mantle upwelling. Instead, the morphologic variations between the three classes of topographic rises are interpreted to indicate the varying influences of lithospheric structure, plume characteristics, and regional tectonic environment. Within each class, variations in topography, gravity, and amount of volcanism may be indicative of differing stages of evolution. The similarity between swell and volcanic volumes for terrestrial and Venusian hotspots implies comparable time-integrated plume strengths for individual upwellings on the two planets.

  13. Modeling of nanosecond pulsed laser processing of polymers in air and water

    DEFF Research Database (Denmark)

    Marla, Deepak; Zhang, Yang; Hattel, Jesper H.

    2018-01-01

    radiation (λ = 1064 nm) of nanosecond pulse duration. The laser–polymer interaction at such wavelengths is purely photo-thermal in nature and the laser–plasma interaction is assumed to occur mainly by inverse-bremsstrahlung photon absorption. The computational model is based on the finite volume method......Laser ablation of polymers in water is known to generate distinct surface characteristics as compared to that in air. In order to understand the role of ambient media during laser ablation of polymers, this paper aims to develop a physics-based model of the process considering the effect of ambient...... media. Therefore, in the present work, models are developed for laser ablation of polymers in air and water considering all the relevant physical phenomena such as laser–polymer interaction, plasma generation, plasma expansion and plasma shielding. The current work focuses on near-infrared laser...

  14. Ionization processes in combined high-voltage nanosecond - laser discharges in inert gas

    Science.gov (United States)

    Starikovskiy, Andrey; Shneider, Mikhail; PU Team

    2016-09-01

    Remote control of plasmas induced by laser radiation in the atmosphere is one of the challenging issues of free space communication, long-distance energy transmission, remote sensing of the atmosphere, and standoff detection of trace gases and bio-threat species. Sequences of laser pulses, as demonstrated by an extensive earlier work, offer an advantageous tool providing access to the control of air-plasma dynamics and optical interactions. The avalanche ionization induced in a pre-ionized region by infrared laser pulses where investigated. Pre-ionization was created by an ionization wave, initiated by high-voltage nanosecond pulse. Then, behind the front of ionization wave extra avalanche ionization was initiated by the focused infrared laser pulse. The experiment was carried out in argon. It is shown that the gas pre-ionization inhibits the laser spark generation under low pressure conditions.

  15. Low-dielectric layer increases nanosecond electric discharges in distilled water

    KAUST Repository

    Hamdan, Ahmad

    2016-10-24

    Electric discharge in liquids is an emerging field of research, and is involved into various environmental applications (water purification, fuel reforming, nanomaterial synthesis, etc.). Increasing the treatment efficiency with simultaneous decreasing of the energy consumption are the main goals of today’s research. Here we present an experimental study of nanosecond discharge in distilled water covered by a layer of dielectric material. We demonstrate through this paper that the discharge efficiency can be improved by changing the interface position regarding the anode tip. The efficiency increase is due to the increase of the discharge probability as well as the plasma volume. The understanding of the experimental results is brought and strengthened by simulating the electric field distribution, using Comsol Multiphysics software. Because the dielectric permittivity (ε) is discontinuous at the interface, the electric field is enhanced by a factor that depends on the relative value of ε of the two liquids. The present result is very promising in future: opportunities for potential applications as well as fundamental studies for discharges in liquid.

  16. Time Resolved Detection of Infrared Synchrotron Radiation at DAΦNE

    International Nuclear Information System (INIS)

    Bocci, A.; Marcelli, A.; Drago, A.; Guidi, M. Cestelli; Pace, E.; Piccinini, M.; Sali, D.; Morini, P.; Piotrowski, J.

    2007-01-01

    Synchrotron radiation is characterized by a very wide spectral emission from IR to X-ray wavelengths and a pulsed structure that is a function of the source time structure. In a storage ring, the typical temporal distance between two bunches, whose duration is a few hundreds of picoseconds, is on the nanosecond scale. Therefore, synchrotron radiation sources are a very powerful tools to perform time-resolved experiments that however need extremely fast detectors. Uncooled IR devices optimized for the mid-IR range with sub-nanosecond response time, are now available and can be used for fast detection of intense IR sources such as synchrotron radiation storage rings. We present here different measurements of the pulsed synchrotron radiation emission at DAΦNE (Double Annular Φ-factory for Nice Experiments), the collider of the Laboratori Nazionali of Frascati (LNF) of the Istituto Nazionale di Fisica Nucleare (INFN), performed with very fast uncooled infrared detectors with a time resolution of a few hundreds of picoseconds. We resolved the emission time structure of the electron bunches of the DAΦNE collider when it works in a normal condition for high energy physics experiments with both photovoltaic and photoconductive detectors. Such a technology should pave the way to new diagnostic methods in storage rings, monitoring also source instabilities and bunch dynamics

  17. Sub-nanosecond Half-life Measurement of the Yrast I{sup π}=5{sup −} State in the N=78 Nucleus {sup 136}{sub 58}Ce using Fast-timing Coincident Gamma-ray Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Alharbi, T. [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); Department of Physics, Faculty of Science in Zulfi, Almajmaah University, P.O. Box 1712, 11932 (Saudi Arabia); Regan, P.H., E-mail: p.regan@surrey.ac.uk [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); National Physical Laboratory, Teddington, Middlesex, TW11 0LW (United Kingdom); Mărginean, N. [Horia Hulubei – National Institute for Physics and Nuclear Engineering (IFIN-HH), Bucharest (Romania); Podolyák, Zs.; Bajoga, A.; Britton, R. [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); Bucurescu, D.; Deleanu, D.; Filipescu, D.; Ghită, D.; Glodariu, T.; Mihai, C. [Horia Hulubei – National Institute for Physics and Nuclear Engineering (IFIN-HH), Bucharest (Romania); Mulholland, K. [School of Engineering, University of the West of Scotland, High Street, Paisley PA1 2BE (United Kingdom); Mărginean, R.; Negret, A.; Nita, C.R. [Horia Hulubei – National Institute for Physics and Nuclear Engineering (IFIN-HH), Bucharest (Romania); Patel, Z. [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); Roberts, O.J. [School of Computing Engineering and Mathematics, University of Brighton, Brighton, BN2 4GJ (United Kingdom); Stroe, L.; Sava, T. [Horia Hulubei – National Institute for Physics and Nuclear Engineering (IFIN-HH), Bucharest (Romania); and others

    2014-06-15

    We report on the measurement of the half-life of the yrast I{sup π}=5{sup −} state in the transitional nucleus {sup 136}Ce using a combined HPGe-LaBr3(Ce) scintillator gamma-ray detection array. The measured value for the E1 decay is approximately half a nanosecond, which corresponds to an E1 decay strength of approximately 2×10{sup −6} Wu. This value is in line with single-particle type E1 decays in this mass region and suggests no sign of additional K-hindrance associated with axially symmetric quadrupole deformations observed for lighter cerium isotopes.

  18. Nanosecond formation of diamond and lonsdaleite by shock compression of graphite.

    Science.gov (United States)

    Kraus, D; Ravasio, A; Gauthier, M; Gericke, D O; Vorberger, J; Frydrych, S; Helfrich, J; Fletcher, L B; Schaumann, G; Nagler, B; Barbrel, B; Bachmann, B; Gamboa, E J; Göde, S; Granados, E; Gregori, G; Lee, H J; Neumayer, P; Schumaker, W; Döppner, T; Falcone, R W; Glenzer, S H; Roth, M

    2016-03-14

    The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery of microscopic diamonds in remnants of explosively driven graphite. Furthermore, shock synthesis of diamond and lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected to happen during violent meteor impacts. Here, we show unprecedented in situ X-ray diffraction measurements of diamond formation on nanosecond timescales by shock compression of pyrolytic as well as polycrystalline graphite to pressures from 19 GPa up to 228 GPa. While we observe the transition to diamond starting at 50 GPa for both pyrolytic and polycrystalline graphite, we also record the direct formation of lonsdaleite above 170 GPa for pyrolytic samples only. Our experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites.

  19. Nanosecond radio bursts from strong plasma turbulence in the Crab pulsar.

    Science.gov (United States)

    Hankins, T H; Kern, J S; Weatherall, J C; Eilek, J A

    2003-03-13

    The Crab pulsar was discovered by the occasional exceptionally bright radio pulses it emits, subsequently dubbed 'giant' pulses. Only two other pulsars are known to emit giant pulses. There is no satisfactory explanation for the occurrence of giant pulses, nor is there a complete theory of the pulsar emission mechanism in general. Competing models for the radio emission mechanism can be distinguished by the temporal structure of their coherent emission. Here we report the discovery of isolated, highly polarized, two-nanosecond subpulses within the giant radio pulses from the Crab pulsar. The plasma structures responsible for these emissions must be smaller than one metre in size, making them by far the smallest objects ever detected and resolved outside the Solar System, and the brightest transient radio sources in the sky. Only one of the current models--the collapse of plasma-turbulent wave packets in the pulsar magnetosphere--can account for the nanopulses we observe.

  20. Ramp time synchronization. [for NASA Deep Space Network

    Science.gov (United States)

    Hietzke, W.

    1979-01-01

    A new method of intercontinental clock synchronization has been developed and proposed for possible use by NASA's Deep Space Network (DSN), using a two-way/three-way radio link with a spacecraft. Analysis of preliminary data indicates that the real-time method has an uncertainty of 0.6 microsec, and it is very likely that further work will decrease the uncertainty. Also, the method is compatible with a variety of nonreal-time analysis techniques, which may reduce the uncertainty down to the tens of nanosecond range.

  1. Comparison of GLONASS and GPS time transfers between two west European time laboratories and VNIIFTRI

    Science.gov (United States)

    Daly, P.; Koshelyaevsky, N. B.; Lewandowski, Wlodzimierz; Petit, Gerard; Thomas, Claudine

    1992-01-01

    The University of Leeds built a Global Positioning System/Global Orbiting Navigation Satellite System (GPS/GLONASS) receiver about five years ago and since then has provided continuous information about GLONASS time and its comparison with GPS time. For the last two years, VNIIFTRI (All Union Institute for Physical, Technical and Radiotechnical Measurements) and some other Soviet time laboratories have used Soviet built GLONASS navigation receivers for time comparisons. Since June 1991, VNIIFTIR has been operating a GPS time receiver on loan from the BIPM (Bureau International des Poids et Mesures). This offered, for the first time, an opportunity for direct comparison of time transfers using GPS and GLONASS. This experiment shows that even with relatively imprecise data recording and processing, in terms of time metrology, GLONASS can provide continental time transfer at a level of several tens of nanoseconds.

  2. Influence of grid resolution in fluid-model simulation of nanosecond dielectric barrier discharge plasma actuator

    Science.gov (United States)

    Hua, Weizhuo; Fukagata, Koji

    2018-04-01

    Two-dimensional numerical simulation of a surface dielectric barrier discharge (SDBD) plasma actuator, driven by a nanosecond voltage pulse, is conducted. A special focus is laid upon the influence of grid resolution on the computational result. It is found that the computational result is not very sensitive to the streamwise grid spacing, whereas the wall-normal grid spacing has a critical influence. In particular, the computed propagation velocity changes discontinuously around the wall-normal grid spacing about 2 μm due to a qualitative change of discharge structure. The present result suggests that a computational grid finer than that was used in most of previous studies is required to correctly capture the structure and dynamics of streamer: when a positive nanosecond voltage pulse is applied to the upper electrode, a streamer forms in the vicinity of upper electrode and propagates along the dielectric surface with a maximum propagation velocity of 2 × 108 cm/s, and a gap with low electron and ion density (i.e., plasma sheath) exists between the streamer and dielectric surface. Difference between the results obtained using the finer and the coarser grid is discussed in detail in terms of the electron transport at a position near the surface. When the finer grid is used, the low electron density near the surface is caused by the absence of ionization avalanche: in that region, the electrons generated by ionization is compensated by drift-diffusion flux. In contrast, when the coarser grid is used, underestimated drift-diffusion flux cannot compensate the electrons generated by ionization, and it leads to an incorrect increase of electron density.

  3. Coastal sea level rise with warming above 2 °C.

    Science.gov (United States)

    Jevrejeva, Svetlana; Jackson, Luke P; Riva, Riccardo E M; Grinsted, Aslak; Moore, John C

    2016-11-22

    Two degrees of global warming above the preindustrial level is widely suggested as an appropriate threshold beyond which climate change risks become unacceptably high. This "2 °C" threshold is likely to be reached between 2040 and 2050 for both Representative Concentration Pathway (RCP) 8.5 and 4.5. Resulting sea level rises will not be globally uniform, due to ocean dynamical processes and changes in gravity associated with water mass redistribution. Here we provide probabilistic sea level rise projections for the global coastline with warming above the 2 °C goal. By 2040, with a 2 °C warming under the RCP8.5 scenario, more than 90% of coastal areas will experience sea level rise exceeding the global estimate of 0.2 m, with up to 0.4 m expected along the Atlantic coast of North America and Norway. With a 5 °C rise by 2100, sea level will rise rapidly, reaching 0.9 m (median), and 80% of the coastline will exceed the global sea level rise at the 95th percentile upper limit of 1.8 m. Under RCP8.5, by 2100, New York may expect rises of 1.09 m, Guangzhou may expect rises of 0.91 m, and Lagos may expect rises of 0.90 m, with the 95th percentile upper limit of 2.24 m, 1.93 m, and 1.92 m, respectively. The coastal communities of rapidly expanding cities in the developing world, and vulnerable tropical coastal ecosystems, will have a very limited time after midcentury to adapt to sea level rises unprecedented since the dawn of the Bronze Age.

  4. Study of nanosecond discharges in H2-air mixtures at atmospheric pressure for plasma assisted combustion applications

    Science.gov (United States)

    Kobayashi, Sumire; Bonaventura, Zdeněk; Tholin, Fabien; Popov, Nikolay A.; Bourdon, Anne

    2017-07-01

    This paper presents 2D simulations of nanosecond discharges between two point electrodes for four different H2-air mixtures defined by their equivalence ratios ϕ (i.e. φ =0, air, φ =0.3, lean mixture, φ =1, stoichiometric mixture and φ =1.5, rich mixture) at atmospheric pressure and at an initial temperature of 1000 K. In a first step, we have shown that the mixture composition has only a very small influence on the discharge dynamics and structure during the streamer phase and up to the formation of the plasma channel between the two point electrodes in H2-air mixtures with φ \\in [0,1.5]. However, as the plasma channel is formed slightly earlier as the equivalence ratio increases, for a given voltage pulse, the duration of the nanosecond spark phase increases as the equivalence ratio increases. As expected, we have shown that excited states of N2 (and in particular N2(A)) and radicals (and in particular O(D), O(P), H and OH) are very efficiently produced during the voltage pulse after the start of the spark phase. After the voltage pulse, and up to 100 ns, the densities of excited states of N2 and of O(D) decrease. Conversely, most of the O(P), H and OH radicals are produced after the voltage pulse due to the dissociative quenching of electronically excited N2. As for radicals, the gas temperature starts increasing after the start of the spark phase. For all studied mixtures, the density of O(P) atoms and the gas temperature reach their maxima after the end of the voltage pulse and the densities of O(P), H and OH radicals and the maximal gas temperature increase as the equivalence ratio increases. We have shown that the production of radicals is the highest on the discharge axis and the distribution of species after the voltage pulse and up to 100 ns has a larger diameter between the electrodes than close to both electrode tips. As for species, the temperature distribution presents two hot spots close to the point electrode tips. The non

  5. Cutting and drilling of carbon fiber reinforced plastics (CFRP) by 70W short pulse nanosecond laser

    Science.gov (United States)

    Jaeschke, Peter; Stolberg, Klaus; Bastick, Stefan; Ziolkowski, Ewa; Roehner, Markus; Suttmann, Oliver; Overmeyer, Ludger

    2014-02-01

    Continuous carbon fibre reinforced plastics (CFRP) are recognized as having a significant lightweight construction potential for a wide variety of industrial applications. However, a today`s barrier for a comprehensive dissemination of CFRP structures is the lack of economic, quick and reliable manufacture processes, e.g. the cutting and drilling steps. In this paper, the capability of using pulsed disk lasers in CFRP machining is discussed. In CFRP processing with NIR lasers, carbon fibers show excellent optical absorption and heat dissipation, contrary to the plastics matrix. Therefore heat dissipation away from the laser focus into the material is driven by heat conduction of the fibres. The matrix is heated indirectly by heat transfer from the fibres. To cut CFRP, it is required to reach the melting temperature for thermoplastic matrix materials or the disintegration temperature for thermoset systems as well as the sublimation temperature of the reinforcing fibers simultaneously. One solution for this problem is to use short pulse nanosecond lasers. We have investigated CFRP cutting and drilling with such a laser (max. 7 mJ @ 10 kHz, 30 ns). This laser offers the opportunity of wide range parameter tuning for systematic process optimization. By applying drilling and cutting operations based on galvanometer scanning techniques in multi-cycle mode, excellent surface and edge characteristics in terms of delamination-free and intact fiber-matrix interface were achieved. The results indicate that nanosecond disk laser machining could consequently be a suitable tool for the automotive and aircraft industry for cutting and drilling steps.

  6. High Efficiency XAFS Data Collection With Sub-Nanosecond Time Resolution

    International Nuclear Information System (INIS)

    Brewe, Dale; Heald, Steve M.; Stern, Edward; Beck, Kenneth M.; Feng, Yejun

    2004-01-01

    Synchrotron-based laser pump/x-ray probe experiments on a ns or faster time scale have typically used ultrafast lasers suffering from the limitation of low repetition rates on the order of 1-10 kHz. This severely limits the data collection efficiency, since the x-ray bunches repeat at a much higher rate. This is particularly critical for XAFS experiments, which require very large S/N ratios (∼ 104 or better) to extract useful EXAFS far above the absorption edge. PNC-CAT has developed an apparatus based on a laser repeating at the rate of the APS bunch repetition frequency of 272 kHz, allowing an increase in data collection efficiency by two orders of magnitude. We have used this apparatus to obtain preliminary results for the time-resolved EXAFS from a 200nm thick polycrystalline Ge film which has been heated by the laser

  7. Nanosecond pulsed electric field ablation of hepatocellular carcinoma.

    Science.gov (United States)

    Beebe, Stephen J; Chen, Xinhua; Liu, Jie A; Schoenbach, Karl H

    2011-01-01

    Hepatocellular carcinoma often evades effective therapy and recurrences are frequent. Recently, nanosecond pulsed electric field (nsPEF) ablation using pulse power technology has emerged as a local-regional, non-thermal, and non-drug therapy for skin cancers. In the studies reported here we use nsPEFs to ablate murine, rat and human HCCs in vitro and an ectopic murine Hepa 1-6 HCC in vivo. Using pulses with 60 or 300 ns and electric fields as high as 60 kV/cm, murine Hepa 1-6, rat N1S1 and human HepG2 HCC are readily eliminated with changes in caspase-3 activity. Interestingly caspase activities increase in the mouse and human model and decrease in the rat model as electric field strengths are increased. In vivo, while sham treated control mice survived an average of 15 days after injection and before humane euthanasia, Hepa 1-6 tumors were eliminated for longer than 50 days with 3 treatments using one hundred pulses with 100 ns at 55 kV/cm. Survival was 40% in mice treated with 30 ns pulses at 55 kV/cm. This study demonstrates that nsPEF ablation is not limited to effectively treating skin cancers and provides a rationale for treating orthotopic hepatocellular carcinoma in pre-clinical applications and ultimately in clinical trials.

  8. Introduction to Time-Resolved Spectroscopy: Nanosecond Transient Absorption and Time-Resolved Fluorescence of Eosin B

    Science.gov (United States)

    Farr, Erik P.; Quintana, Jason C.; Reynoso, Vanessa; Ruberry, Josiah D.; Shin, Wook R.; Swartz, Kevin R.

    2018-01-01

    Here we present a new undergraduate laboratory that will introduce the concepts of time-resolved spectroscopy and provide insight into the natural time scales on which chemical dynamics occur through direct measurement. A quantitative treatment of the acquired data will provide a deeper understanding of the role of quantum mechanics and various…

  9. Nanosecond and femtosecond ablation of La0.6Ca0.4CoO3: a comparison between plume dynamics and composition of the films

    DEFF Research Database (Denmark)

    Canulescu, Stela; Papadopoulou, E.; Anglos, D.

    2011-01-01

    Thin films of La0.6Ca0.4CoO3 were grown by pulsed laser ablation with nanosecond and femtosecond pulses. The films deposited with femtosecond pulses (248 nm, 500 fs pulse duration) exhibit a higher surface roughness and deficiency in the cobalt content compared to the films deposited with nanosec......Thin films of La0.6Ca0.4CoO3 were grown by pulsed laser ablation with nanosecond and femtosecond pulses. The films deposited with femtosecond pulses (248 nm, 500 fs pulse duration) exhibit a higher surface roughness and deficiency in the cobalt content compared to the films deposited...... and in a background pressure of 60 Pa of oxygen. The ns-induced plume in vacuum exhibits a spherical shape, while for femtosecond ablation the plume is more elongated along the expansion direction, but with similar velocities for ns and fs laser ablation. In the case of ablation in the background gas similar...

  10. Field monitoring of column shortenings in a high-rise building during construction.

    Science.gov (United States)

    Choi, Se Woon; Kim, Yousok; Kim, Jong Moon; Park, Hyo Seon

    2013-10-24

    The automatic monitoring of shortenings of vertical members in high-rise buildings under construction is a challenging issue in the high-rise building construction field. In this study, a practical system for monitoring column shortening in a high-rise building under construction is presented. The proposed monitoring system comprises the following components: (1) a wireless sensing system and (2) the corresponding monitoring software. The wireless sensing system comprises the sensors and energy-efficient wireless sensing units (sensor nodes, master nodes, and repeater nodes), which automate the processes for measuring the strains of vertical members and transmitting the measured data to the remote server. The monitoring software enables construction administrators to monitor real-time data collected by the server via an Internet connection. The proposed monitoring system is applied to actual 66-floor and 72-floor high-rise buildings under construction. The system enables automatic and real-time measurements of the shortening of vertical members, which can result in more precise construction.

  11. Very Fast Current Diagnostic for Linear Pulsed Beams

    Directory of Open Access Journals (Sweden)

    Nassisi Vincenzo

    2018-01-01

    Full Text Available Fast current pulses manage lasers and particle accelerators and require sophisticate systems to be detected. At today Rogowski coils are well known. They are designed and built with a toroidal structure. In recently application, flat transmission lines are imploded and for this reason we develop a linear Rogowski coil to detect current pulses inside flat conductors. To get deep information from the system, it was approached by means of the theory of the transmission lines. The coil we build presents a resistance but it doesn’t influence the rise time of the response, instead the integrating time. We also studied the influence of the magnetic properties of coil support. The new device was able to record pulses of more hundred nanoseconds depending on the inductance, load impedance and resistance of the coil. Furthermore, its response was characterized by a sub-nanosecond rise time (~100 ps, The attenuation coefficient depends mainly on the turn number of the coil, while the quality of the response depends both on the manufacture quality of the coil and on the magnetic core characteristics. In biophysical applications often, a double line is employed in order to have a sample as control and a sample stressed by a light source. So, in this case we build two equal plane lines by 100 Ω characteristic resistance connected in parallel. We diagnosed the current present in a line. The attenuation factor resulted to be 11,5 A/V.

  12. Very Fast Current Diagnostic for Linear Pulsed Beams

    Science.gov (United States)

    Nassisi, Vincenzo; Delle Side, Domenico; Turco, Vito

    2018-01-01

    Fast current pulses manage lasers and particle accelerators and require sophisticate systems to be detected. At today Rogowski coils are well known. They are designed and built with a toroidal structure. In recently application, flat transmission lines are imploded and for this reason we develop a linear Rogowski coil to detect current pulses inside flat conductors. To get deep information from the system, it was approached by means of the theory of the transmission lines. The coil we build presents a resistance but it doesn't influence the rise time of the response, instead the integrating time. We also studied the influence of the magnetic properties of coil support. The new device was able to record pulses of more hundred nanoseconds depending on the inductance, load impedance and resistance of the coil. Furthermore, its response was characterized by a sub-nanosecond rise time ( 100 ps), The attenuation coefficient depends mainly on the turn number of the coil, while the quality of the response depends both on the manufacture quality of the coil and on the magnetic core characteristics. In biophysical applications often, a double line is employed in order to have a sample as control and a sample stressed by a light source. So, in this case we build two equal plane lines by 100 Ω characteristic resistance connected in parallel. We diagnosed the current present in a line. The attenuation factor resulted to be 11,5 A/V.

  13. Nanosecond laser scribing of CIGS thin film solar cell based on ITO bottom contact

    Science.gov (United States)

    Kuk, Seungkuk; Wang, Zhen; Fu, Shi; Zhang, Tao; Yu, Yi Yin; Choi, JaeMyung; Jeong, Jeung-hyun; Hwang, David J.

    2018-03-01

    Cu(In,Ga)Se2 (CIGS) thin films, a promising photovoltaic architecture, have mainly relied on Molybdenum for the bottom contact. However, the opaque nature of Molybdenum (Mo) poses limitations in module level fabrication by laser scribing as a preferred method for interconnect. We examined the P1, P2, and P3 laser scribing processes on CIGS photovoltaic architecture on the indium tin oxide (ITO) bottom contact with a cost-effective nanosecond pulsed laser of 532 nm wavelength. Laser illuminated from the substrate side, enabled by the transparent bottom contact, facilitated selective laser energy deposition onto relevant interfaces towards high-quality scribing. Parametric tuning procedures are described in conjunction with experimental and numerical investigation of relevant mechanisms, and preliminary mini-module fabrication results are also presented.

  14. An Empirical Fitting Method to Type Ia Supernova Light Curves. III. A Three-parameter Relationship: Peak Magnitude, Rise Time, and Photospheric Velocity

    Science.gov (United States)

    Zheng, WeiKang; Kelly, Patrick L.; Filippenko, Alexei V.

    2018-05-01

    We examine the relationship between three parameters of Type Ia supernovae (SNe Ia): peak magnitude, rise time, and photospheric velocity at the time of peak brightness. The peak magnitude is corrected for extinction using an estimate determined from MLCS2k2 fitting. The rise time is measured from the well-observed B-band light curve with the first detection at least 1 mag fainter than the peak magnitude, and the photospheric velocity is measured from the strong absorption feature of Si II λ6355 at the time of peak brightness. We model the relationship among these three parameters using an expanding fireball with two assumptions: (a) the optical emission is approximately that of a blackbody, and (b) the photospheric temperatures of all SNe Ia are the same at the time of peak brightness. We compare the precision of the distance residuals inferred using this physically motivated model against those from the empirical Phillips relation and the MLCS2k2 method for 47 low-redshift SNe Ia (0.005 Ia in our sample with higher velocities are inferred to be intrinsically fainter. Eliminating the high-velocity SNe and applying a more stringent extinction cut to obtain a “low-v golden sample” of 22 SNe, we obtain significantly reduced scatter of 0.108 ± 0.018 mag in the new relation, better than those of the Phillips relation and the MLCS2k2 method. For 250 km s‑1 of residual peculiar motions, we find 68% and 95% upper limits on the intrinsic scatter of 0.07 and 0.10 mag, respectively.

  15. Decolorization of methylene blue in aqueous suspensions of gold nanoparticles using parallel nanosecond pulsed laser.

    Science.gov (United States)

    Zong, Yan P; Liu, Xian H; Du, Xi W; Lu, Yi R; Wang, Mei Y; Wang, Guang Y

    2013-01-01

    Using 532 nm parallel nanosecond pulsed laser, the decolorization of methylene blue (MB) in aqueous suspensions of gold nanoparticles (GNPs) was studied. The effects of various experimental parameters, such as irradiation time, laser energy, and initial MB concentration on the decolorization rate were investigated. Experiments using real samples of textile dyeing wastewater were also carried out to examine the effectiveness of the method in more complex samples. From the results, the following conclusions may be drawn: (i) Under the optimum conditions (pH 7.19, 135 mJ laser energy, 4 mg/L MB concentration, and 11.6 mg/L GNP concentration), the rate of MB decolorization could reach 94% in 15 min. The decolorization follows pseudo-first-order kinetics; (ii) The amount of MB decreased rapidly during the decolorization. No intermediates of the decolorization could be detected by high-performance liquid chromatography. These observations indicate that MB was decolorized through a very rapid degradation mechanism; (iii) The rate of MB decolorization increased with the increase in laser energy (at laser energies of 0 to 135 mJ); and, (iv) The efficient decolorization of MB in real samples of textile dyeing wastewater was achieved at a decolorization rate of about 85% in 15 min.

  16. Hybrid Ti:Sapphire / KrF laser facility GARPUN for combined subpicosecond/nanosecond laser-matter interaction studies

    International Nuclear Information System (INIS)

    Zvorykin, V.D.; Ionin, A.A.; Konyashcenko, A.V.; Levchenko, A.O.; Krokhin, O.N.; Mesyats, G.A.; Molchanov, A.G.; Rorulev, M.A.

    2006-01-01

    Complete test of publication follows. Hybrid laser facility consisting of Ti:Sapphire front end, 3ω converter, and e-beam-pumped large-aperture KrF amplifiers is under construction to generate combined sub-picosecond/nanosecond pulses in UV spectral range at 248-nm wavelength. This is a part of the Petawatt excimer laser project started at P.N. Lebedev Physical Institute. In comparison with commonly used solid-state chirped-pulse amplifiers (CPA), KrF amplifiers have following advantages: (i) low-density gaseous matter with three orders of magnitude lower non-linear refraction index has a small value of B-integral and negligible pulse distortion; (ii) short radiation lifetime τ r = 6 ns of the upper laser level of KrF(B-X) transition (with accounting for collisions τ c ∼ 2 ns), that means the population inversion is recovered each 2 ns during the pumping time, which is typically τ p ≥ 100 ns for technical reasons. Thus, it might be possible eliminating of very costly large-aperture compressor gratings and to amplify both short τ sh c and long τ long ≥ τ c pulses in the same amplifiers, as a short pulse does not affect the gain during the most of pumping. This gives a unique opportunity for realization of fast-ignition scheme in Inertial Confinement Fusion using large-scale KrF drivers. The Ti:Sapphire front end 'Start 248M' currently operates with the following parameters: rep rate 10 Hz, pulse energy and duration at fundamental wavelength (744 nm) > 8 mJ and 0.5 mJ and 0.4 mJ, 740 nm) and multi-pass amplifier (10 Hz, > 15 mJ, 740 nm), both pumped by 2ω pulsed Lotis LS-2134 Nd:YAG laser (10 Hz, 10 ns, 532 nm) with distributed energies of 5 and 70 mJ, two-gratings compressor, and 3ω converter with two BBO crystals and total efficiency 8%. EMG 150MSC Lambda Physik KrF laser is used afterwards to generate ns pulses and to amplify fs pulses in its two separate discharge chambers. Two e-beam pumped KrF amplifiers Berdysh and GARPUN with active volumes 10

  17. Creation of excitations and defects in insulating materials by high-current-density electron beams of nanosecond pulse duration

    International Nuclear Information System (INIS)

    Vaisburd, D.I.; Evdokimov, K.E.

    2005-01-01

    The paper is concerned with fast and ultra-fast processes in insulating materials under the irradiation by a high-current-density electron beam of a nanosecond pulse duration. The inflation process induced by the interaction of a high-intensity electron beam with a dielectric is examined. The ''instantaneous'' distribution of non-ionizing electrons and holes is one of the most important stages of the process. Ionization-passive electrons and holes make the main contribution to many fast processes with a characteristic time in the range 10 -14 /10 -12 s: high-energy conductivity, intraband luminescence, etc. A technique was developed for calculation of the ''instantaneous'' distribution of non-ionizing electrons and holes in a dielectric prior to electron-phonon relaxation. The following experimental effects are considered: intraband luminescence, coexistence of intraband electron luminescence and band-to-band hole luminescence in CsI, high energy conductivity; generation of mechanical fields and their interaction with cracks and dislocations. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. A method for the formation of Pt metal nanoparticle arrays using nanosecond pulsed laser dewetting

    Energy Technology Data Exchange (ETDEWEB)

    Owusu-Ansah, Ebenezer; Horwood, Corie A.; Birss, Viola I.; Shi, Yujun J., E-mail: shiy@ucalgary.ca [Department of Chemistry, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); El-Sayed, Hany A. [Institute for Technical Electrochemistry, Technische Universität München, D-85748 Garching (Germany)

    2015-05-18

    Nanosecond pulsed laser dewetting of Pt thin films, deposited on a dimpled Ta (DT) surface, has been studied here in order to form ordered Pt nanoparticle (NP) arrays. The DT substrate was fabricated via a simple electrochemical anodization process in a highly concentrated H{sub 2}SO{sub 4} and HF solution. Pt thin films (3–5 nm) were sputter coated on DT and then dewetted under vacuum to generate NPs using a 355 nm laser radiation (6–9 ns, 10 Hz). The threshold laser fluence to fully dewet a 3.5 nm thick Pt film was determined to be 300 mJ/cm{sup 2}. Our experiments have shown that shorter irradiation times (≤60 s) produce smaller nanoparticles with more uniform sizes, while longer times (>60 s) give large nanoparticles with wider size distributions. The optimum laser irradiation time of 1 s (10 pulses) has led to the formation of highly ordered Pt nanoparticle arrays with an average nanoparticle size of 26 ± 3 nm with no substrate deformation. At the optimum condition of 1 s and 500 mJ/cm{sup 2}, as many as 85% of the dewetted NPs were found neatly in the well-defined dimples. This work has demonstrated that pulsed laser dewetting of Pt thin films on a pre-patterned dimpled substrate is an efficient and powerful technique to produce highly ordered Pt nanoparticle arrays. This method can thus be used to produce arrays of other high-melting-point metal nanoparticles for a range of applications, including electrocatalysis, functionalized nanomaterials, and analytical purposes.

  19. Diagnostics from three rising submillimeter bursts

    International Nuclear Information System (INIS)

    Zhou, Ai-Hua; Li, Jian-Ping; Wang, Xin-Dong

    2016-01-01

    In this paper we investigate three novel rising submillimeter (THz) bursts that occurred sequentially in Super Active Region NOAA 10486. The average rising rate of the flux density above 200 GHz is only 20 sfu GHz −1 (corresponding to spectral index α of 1.6) for the THz spectral components of the 2003 October 28 and November 4 bursts, but it attained values of 235 sfu GHz −1 (α = 4.8) in the 2003 November 2 burst. The steeply rising THz spectrum can be produced by a population of highly relativistic electrons with a low-energy cutoff of 1 MeV, but it only requires a low-energy cutoff of 30 keV for the two slowly rising THz bursts, via gyrosynchrotron (GS) radiation based on our numerical simulations of burst spectra in the magnetic dipole field case. The electron density variation is much larger in the THz source than in the microwave (MW) source. It is interesting that the THz source radius decreased by 20%–50% during the decay phase for the three events, but the MW source increased by 28% for the 2003 November 2 event. In the paper we will present a formula that can be used to calculate the energy released by ultrarelativistic electrons, taking the relativistic correction into account for the first time. We find that the energy released by energetic electrons in the THz source exceeds that in the MW source due to the strong GS radiation loss in the THz range, although the modeled THz source area is 3–4 orders smaller than the modeled MW source one. The total energies released by energetic electrons via the GS radiation in radio sources are estimated, respectively, to be 5.2 × 10 33 , 3.9 × 10 33 and 3.7 × 10 32 erg for the October 28, November 2 and 4 bursts, which are 131, 76 and 4 times as large as the thermal energies of 2.9 × 10 31 , 2.1 × 10 31 and 5.2 × 10 31 erg estimated from soft X-ray GOES observations. (paper)

  20. Determination of Temperature Rise and Temperature Differentials of CEMII/B-V Cement for 20MPa Mass Concrete using Adiabatic Temperature Rise Data

    Science.gov (United States)

    Chee Siang, GO

    2017-07-01

    Experimental test was carried out to determine the temperature rise characteristics of Portland-Fly-Ash Cement (CEM II/B-V, 42.5N) of Blaine fineness 418.6m2/kg and 444.6m2/kg respectively for 20MPa mass concrete under adiabatic condition. The estimation on adiabatic temperature rise by way of CIRIA C660 method (Construction Industry Research & Information Information) was adopted to verify and validate the hot-box test results by simulating the heat generation curve of the concrete under semi-adiabatic condition. Test result found that Portland fly-ash cement has exhibited decrease in the peak value of temperature rise and maximum temperature rise rate. The result showed that the temperature development and distribution profile, which is directly contributed from the heat of hydration of cement with time, is affected by the insulation, initial placing temperature, geometry and size of concrete mass. The mock up data showing the measured temperature differential is significantly lower than the technical specifications 20°C temperature differential requirement and the 27.7°C limiting temperature differential for granite aggregate concrete as stipulated in BS8110-2: 1985. The concrete strength test result revealed that the 28 days cubes compressive strength was above the stipulated 20MPa characteristic strength at 90 days. The test demonstrated that with proper concrete mix design, the use of Portland flyash cement, combination of chilled water and flake ice, and good insulation is effective in reducing peak temperature rise, temperature differential, and lower adiabatic temperature rise for mass concrete pours. As far as the determined adiabatic temperature rise result was concern, the established result could be inferred for in-situ thermal properties of 20MPa mass concrete application, as the result could be repeatable on account of similar type of constituent materials and concrete mix design adopted for permanent works at project site.

  1. Differences in Nanosecond Laser Ablation and Deposition of Tungsten, Boron, and WB2/B Composite due to Optical Properties

    Directory of Open Access Journals (Sweden)

    Tomasz Moscicki

    2016-01-01

    Full Text Available The first attempt to the deposition of WB3 films using nanosecond Nd:YAG laser demonstrated that deposited coatings are superhard. However, they have very high roughness. The deposited films consisted mainly of droplets. Therefore, in the present work, the explanation of this phenomenon is conducted. The interaction of Nd:YAG nanosecond laser pulse with tungsten, boron, and WB2/B target during ablation is investigated. The studies show the fundamental differences in ablation of those materials. The ablation of tungsten is thermal and occurs due to only evaporation. In the same conditions, during ablation of boron, the phase explosion and/or fragmentation due to recoil pressure is observed. The deposited films have a significant contribution of big debris with irregular shape. In the case of WB2/B composite, ablation is significantly different. The ablation seems to be the detonation in the liquid phase. The deposition mechanism is related mainly to the mechanical transport of the target material in the form of droplets, while the gaseous phase plays marginal role. The main origin of differences is optical properties of studied materials. A method estimating phase explosion occurrence based on material data such as critical temperature, thermal diffusivity, and optical properties is shown. Moreover, the effect of laser wavelength on the ablation process and the quality of the deposited films is discussed.

  2. Production of simplex RNS and ROS by nanosecond pulse N2/O2 plasma jets with homogeneous shielding gas for inducing myeloma cell apoptosis

    Science.gov (United States)

    Liu, Zhijie; Xu, Dehui; Liu, Dingxin; Cui, Qingjie; Cai, Haifeng; Li, Qiaosong; Chen, Hailan; Kong, Michael G.

    2017-05-01

    In this paper, atmospheric pressure N2/O2 plasma jets with homogeneous shielding gas excited by nanosecond pulse are obtained to generate simplex reactive nitrogen species (RNS) and reactive oxygen species (ROS), respectively, for the purpose of studying the simplex RNS and ROS to induce the myeloma cell apoptosis with the same discharge power. The results reveal that the cell death rate by the N2 plasma jet with N2 shielding gas is about two times that of the O2 plasma jet with O2 shielding gas for the equivalent treatment time. By diagnosing the reactive species of ONOO-, H2O2, OH and \\text{O}2- in medium, our findings suggest the cell death rate after plasma jets treatment has a positive correlation with the concentration of ONOO-. Therefore, the ONOO- in medium is thought to play an important role in the process of inducing myeloma cell apoptosis.

  3. Beam-dump kicker magnets

    International Nuclear Information System (INIS)

    Bulos, F.; Odian, A.; Tomlin, B.

    1983-01-01

    The beam-dump kicker magnets are located in the final focus region and, in conjunction with septum magnets, extract the beams after they have passed the interaction point (IP) and direct them to their respective dumps. Two schemes for these kickers have been under consideration; ferrite transmission line magnets utilizing technology common with damping rings and positron target kickers, and current loop magnets which are possible only for the dump kickers, where the rise time of the magnetic pulse can be comparatively longer; approximately 400 nanoseconds as compared with 50 nanoseconds for the others. A prototype ferrite kicker has been built and is undergoing tests. Since the current loop requires lower voltage and power plus some additional savings in cost, we decided to build and test a prototype. This note describes in detail an optimized design for the current loop magnets and their associated pulse circuitry

  4. Direct modification of silicon surface by nanosecond laser interference lithography

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dapeng [JR3CN and CNM (Changchun University of Science and Technology), Changchun 130022 (China); JR3CN and IRAC (University of Bedfordshire), Luton LU1 3JU (United Kingdom); Wang, Zuobin, E-mail: wangz@cust.edu.cn [JR3CN and CNM (Changchun University of Science and Technology), Changchun 130022 (China); JR3CN and IRAC (University of Bedfordshire), Luton LU1 3JU (United Kingdom); Zhang, Ziang [JR3CN and CNM (Changchun University of Science and Technology), Changchun 130022 (China); Yue, Yong [JR3CN and CNM (Changchun University of Science and Technology), Changchun 130022 (China); JR3CN and IRAC (University of Bedfordshire), Luton LU1 3JU (United Kingdom); Li, Dayou [JR3CN and IRAC (University of Bedfordshire), Luton LU1 3JU (United Kingdom); Maple, Carsten [JR3CN and CNM (Changchun University of Science and Technology), Changchun 130022 (China); JR3CN and IRAC (University of Bedfordshire), Luton LU1 3JU (United Kingdom)

    2013-10-01

    Periodic and quasi-periodic structures on silicon surface have numerous significant applications in photoelectronics and surface engineering. A number of technologies have been developed to fabricate the structures in various research fields. In this work, we take the strategy of direct nanosecond laser interference lithography technology, and focus on the silicon material to create different well-defined surface structures based on theoretical analysis of the formation of laser interference patterns. Two, three and four-beam laser interference systems were set up to fabricate the grating, regular triangle and square structures on silicon surfaces, respectively. From the AFM micrographs, the critical features of structures have a dependence on laser fluences. For a relative low laser fluence, grating and dot structures formed with bumps due to the Marangoni Effect. With the increase of laser fluences, melt and evaporation behaviors can be responsible for the laser modification. By properly selecting the process parameters, well-defined grating and dot structures can been achieved. It can be demonstrated that direct laser interference lithography is a facile and efficient technology with the advantage of a single process procedure over macroscale areas for the fabrication of micro and nano structures.

  5. Environmental temperature affects physiology and survival of nanosecond pulsed electric field-treated cells.

    Science.gov (United States)

    Yin, Shengyong; Miao, Xudong; Zhang, Xueming; Chen, Xinhua; Wen, Hao

    2018-02-01

    Nanosecond pulsed electric field (nsPEF) is a novel non-thermal tumor ablation technique. However, how nsPEF affect cell physiology at different environmental temperature is still kept unknown. But this issue is of critical clinical practice relevance. This work aim to investigate how nsPEF treated cancer cells react to different environmental temperatures (0, 4, 25, and 37°C). Their cell viability, apoptosis, mitochondrial membrane potential, and reactive oxygen species (ROS) were examined. Lower temperature resulted in higher apoptosis rate, decreased mitochondria membrane potential, and increased ROS levels. Sucrose and N-acetylcysteine (NAC) pre-incubation inhibit ROS generation and increase cell survival, protecting nsPEF-treated cells from low temperature-caused cell death. This work provides an experimental basis for hypothermia and fluid transfusion during nsPEF ablation with anesthesia. © 2017 Wiley Periodicals, Inc.

  6. Decomposition of methane to hydrogen using nanosecond pulsed plasma reactor with different active volumes, voltages and frequencies

    International Nuclear Information System (INIS)

    Khalifeh, Omid; Mosallanejad, Amin; Taghvaei, Hamed; Rahimpour, Mohammad Reza; Shariati, Alireza

    2016-01-01

    Highlights: • CH 4 conversion into H 2 is investigated in a nanosecond pulsed DBD reactor. • The absence of CO and CO 2 in the product gas is highly favorable. • Effects of external electrode length, applied voltage and frequency are examined. • The maximum efficiency of 7.23% is achieved at the electrode length of 15 cm. • The maximum CH 4 conversion of 87.2% is obtained at discharge power 268.92 W. - Abstract: In this paper, the methane conversion into hydrogen is investigated experimentally in a nanosecond pulsed DBD reactor. In order to achieve pure hydrogen production with minimum power consumption, effects of some operating parameters including external electrode length, applied voltage and pulse repetition frequency have been evaluated. Results show that although higher CH 4 conversion and H 2 concentration can be obtained at longer electrode lengths, higher applied voltages and pulse repetition frequencies, these parameters should be optimized for efficient hydrogen production. Actually, the maximum CH 4 conversion of 87.2% and maximum hydrogen percentage of 80% are obtained at the external electrode length, discharge power, voltage and frequency of 15 cm, 268.92 W, 12 kV and 10 kHz, respectively. However, the maximum efficiency of 7.23% is achieved at the external electrode length of 15 cm, applied voltage of 6 kV, pulse repetition frequency of 0.9 kHz and discharge power of 4 W. Furthermore, at this condition, due to low temperature of discharge zone very little amount of solid carbon was observed on the inner electrode surface of the reactor.

  7. Methods of erection of high-rise buildings

    Science.gov (United States)

    Cherednichenko, Nadezhda; Oleinik, Pavel

    2018-03-01

    The article contains the factors determining the choice of methods for organizing the construction and production of construction and installation work for the construction of high-rise buildings. There are also indicated specific features of their underground parts, characterized by powerful slab-pile foundations, large volumes of earthworks, reinforced bases and foundations for assembly cranes. The work cycle is considered when using reinforced concrete, steel and combined skeletons of high-rise buildings; the areas of application of flow, separate and complex methods are being disclosed. The main conditions for the erection of high-rise buildings and their components are singled out: the choice of formwork systems, delivery and lifting of concrete mixes, installation of reinforcement, the formation of lifting and transporting and auxiliary equipment. The article prescribes the reserves of reduction in the duration of construction due to the creation of: complex mechanized technologies for the efficient construction of foundations in various soil conditions, including in the heaving, swelling, hindered, subsidence, bulk, water-saturated forms; complex mechanized technologies for the erection of monolithic reinforced concrete structures, taking into account the winter conditions of production and the use of mobile concrete-laying complexes and new generation machines; modular formwork systems, distinguished by their versatility, ease, simplicity in operation suitable for complex high-rise construction; more perfect methodology and the development of a set of progressive organizational and technological solutions that ensure a rational relationship between the processes of production and their maximum overlap in time and space.

  8. On the design of high-rise buildings with a specified level of reliability

    Science.gov (United States)

    Dolganov, Andrey; Kagan, Pavel

    2018-03-01

    High-rise buildings have a specificity, which significantly distinguishes them from traditional buildings of high-rise and multi-storey buildings. Steel structures in high-rise buildings are advisable to be used in earthquake-proof regions, since steel, due to its plasticity, provides damping of the kinetic energy of seismic impacts. These aspects should be taken into account when choosing a structural scheme of a high-rise building and designing load-bearing structures. Currently, modern regulatory documents do not quantify the reliability of structures. Although the problem of assigning an optimal level of reliability has existed for a long time. The article shows the possibility of designing metal structures of high-rise buildings with specified reliability. Currently, modern regulatory documents do not quantify the reliability of high-rise buildings. Although the problem of assigning an optimal level of reliability has existed for a long time. It is proposed to establish the value of reliability 0.99865 (3σ) for constructions of buildings and structures of a normal level of responsibility in calculations for the first group of limiting states. For increased (construction of high-rise buildings) and reduced levels of responsibility for the provision of load-bearing capacity, it is proposed to assign respectively 0.99997 (4σ) and 0.97725 (2σ). The coefficients of the use of the cross section of a metal beam for different levels of security are given.

  9. Nanosecond time-resolved EPR in pulse radiolysis via the spin echo method

    International Nuclear Information System (INIS)

    Trifunac, A.D.; Norris, J.R.; Lawler, R.G.

    1979-01-01

    The design and operation of a time-resolved electron spin echo spectrometer suitable for detecting transient radicals produced by 3 MeV electron radiolysis is described. Two modes of operation are available: Field swept mode which generates a normal EPR spectrum and kinetic mode in which the time dependence of a single EPR line is monitored. Techniques which may be used to minimize the effects of nonideal microwave pulses and overlapping sample tube signals are described. The principal advantages of the spin echo method over other time-resolved EPR methods are: (1) Improved time resolution (presently approx.30--50 nsec) allows monitoring of fast changes in EPR signals of transient radicals, (2) Lower susceptibility to interference between the EPR signal and the electron beam pulse at short times, and (3) Lack of dependence of transient signals on microwave field amplitude or static field inhomogeneity at short times. The performance of the instrument is illustrated using CIDEP from acetate radical formed in pulsed radiolysis of aqueous solutions of potassium acetate. The relaxation time and CIDEP enhancement factor obtained for this radical using the spin echo method compare favorably with previous determinations using direct detection EPR. Radical decay rates yield estimates of initial radical concentrations of 10 -4 10 -3 M per electron pulse. The Bloch equations are solved to give an expression for the echo signal for samples exhibiting CIDEP using arbitrary microwave pulse widths and distributions of Larmor frequencies. Conditions are discussed under which the time-dependent signal would be distorted by deviations from an ideal nonselective 90 0 --tau--180 0 pulse sequence

  10. Thermally activated delayed fluorescence of fluorescein derivative for time-resolved and confocal fluorescence imaging.

    Science.gov (United States)

    Xiong, Xiaoqing; Song, Fengling; Wang, Jingyun; Zhang, Yukang; Xue, Yingying; Sun, Liangliang; Jiang, Na; Gao, Pan; Tian, Lu; Peng, Xiaojun

    2014-07-09

    Compared with fluorescence imaging utilizing fluorophores whose lifetimes are in the order of nanoseconds, time-resolved fluorescence microscopy has more advantages in monitoring target fluorescence. In this work, compound DCF-MPYM, which is based on a fluorescein derivative, showed long-lived luminescence (22.11 μs in deaerated ethanol) and was used in time-resolved fluorescence imaging in living cells. Both nanosecond time-resolved transient difference absorption spectra and time-correlated single-photon counting (TCSPC) were employed to explain the long lifetime of the compound, which is rare in pure organic fluorophores without rare earth metals and heavy atoms. A mechanism of thermally activated delayed fluorescence (TADF) that considers the long wavelength fluorescence, large Stokes shift, and long-lived triplet state of DCF-MPYM was proposed. The energy gap (ΔEST) of DCF-MPYM between the singlet and triplet state was determined to be 28.36 meV by the decay rate of DF as a function of temperature. The ΔE(ST) was small enough to allow efficient intersystem crossing (ISC) and reverse ISC, leading to efficient TADF at room temperature. The straightforward synthesis of DCF-MPYM and wide availability of its starting materials contribute to the excellent potential of the compound to replace luminescent lanthanide complexes in future time-resolved imaging technologies.

  11. Effect of nanosecond UV laser irradiation on luminescence and absorption in silver- and copper-containing phosphate glasses

    Science.gov (United States)

    Murashov, A. A.; Sidorov, A. I.; Stoliarchuk, M. V.

    2018-03-01

    Experimental evidence is presented that nanosecond UV laser irradiation of silver- and copper-containing barium phosphate glasses leads to luminescence quenching in the visible range. Subsequent heat treatment induces an absorption in the range 350–500 nm. These effects are due to the ionisation and fragmentation of subnanometre molecular clusters by laser radiation and subsequent (heat treatment-induced) formation of nanoparticles possessing plasmon resonance. Our numerical modelling results demonstrate the feasibility of producing stable AgnCum hybrid molecular clusters in glass. Local modification of the optical properties of glass by laser light can be used for optical information recording.

  12. SPHINX: a generator based on 1 microsecond current rise time LTD stages. Status and first results for production of soft X-ray radiation

    International Nuclear Information System (INIS)

    Mangeant, Ch.; Roques, B.; Cadiergues, R.

    2005-01-01

    SPHINX is the new name of the facility developed for soft X-ray production. This facility is based on the ECF2 generator which was designed as a 1-3 MJ, 1 μs rise time, 5-10 MA current driver. We present a detailed view of the technology used for the capacitor bank, for the central vacuum part and for the Z-pinch loads [ru

  13. Regional approaches in high-rise construction

    Science.gov (United States)

    Iconopisceva, O. G.; Proskurin, G. A.

    2018-03-01

    The evolutionary process of high-rise construction is in the article focus. The aim of the study was to create a retrospective matrix reflecting the tasks of the study such as: structuring the most iconic high-rise objects within historic boundaries. The study is based on contemporary experience of high-rise construction in different countries. The main directions and regional specifics in the field of high-rise construction as well as factors influencing the further evolution process are analyzed. The main changes in architectural stylistics, form-building, constructive solutions that focus on the principles of energy efficiency and bio positivity of "sustainable buildings", as well as the search for a new typology are noted. The most universal constructive methods and solutions that turned out to be particularly popular are generalized. The new typology of high-rises and individual approach to urban context are noted. The results of the study as a graphical scheme made it possible to represent the whole high-rise evolution. The new spatial forms of high-rises lead them to new role within the urban environments. Futuristic hyperscalable concepts take the autonomous urban space functions itself and demonstrate us how high-rises can replace multifunctional urban fabric, developing it inside their shells.

  14. The Climate Science Special Report: Rising Seas and Changing Oceans

    Science.gov (United States)

    Kopp, R. E.

    2017-12-01

    GMSL has risen by about 16-21 cm since 1900. Ocean heat content has increased at all depths since the 1960s, and global mean sea-surface temperature increased 0.7°C/century between 1900 to 2016. Human activity contributed substantially to generating a rate of GMSL rise since 1900 faster than during any preceding century in at least 2800 years. A new set of six sea-level rise scenarios, spanning a range from 30 cm to 250 cm of 21st century GMSL rise, were developed for the CSSR. The lower scenario is based on linearly extrapolating the past two decades' rate of rise. The upper scenario is informed by literature estimates of maximum physically plausible values, observations indicating the onset of marine ice sheet instability in parts of West Antarctica, and modeling of ice-cliff and ice-shelf instability mechanisms. The new scenarios include localized projections along US coastlines. There is significant variability around the US, with rates of rise likely greater than GMSL rise in the US Northeast and the western Gulf of Mexico. Under scenarios involving extreme Antarctic contributions, regional rise would be greater than GMSL rise along almost all US coastlines. Historical sea-level rise has already driven a 5- to 10-fold increase in minor tidal flooding in several US coastal cities since the 1960s. Under the CSSR's Intermediate sea-level rise scenario (1.0 m of GMSL rise in 2100) , a majority of NOAA tide gauge locations will by 2040 experience the historical 5-year coastal flood about 5 times per year. Ocean changes are not limited to rising sea levels. Ocean pH is decreasing at a rate that may be unparalleled in the last 66 million years. Along coastlines, ocean acidification can be enhanced by changes in the upwelling (particularly along the US Pacific Coast); by episodic, climate change-enhanced increases in freshwater input (particularly along the US Atlantic Coast); and by the enhancement of biological respiration by nutrient runoff. Climate models project

  15. Soil Structure Interaction Effect on High Rise and Low Rise Buildings

    OpenAIRE

    Divya Pathak; PAresh H. SHAH

    2000-01-01

    Effect of supporting soil on the response of structure has been analyzed in the present study. A low rise (G+ 5 storey) and a high rise (G+12 storey) building has been taken for the analysis. For both type of buildings, the response of building with and without consideration of soil structure interaction effect has been compared.Without interaction case is the case in which ends of the structure are assumed to be fixed while in interaction case, structure is assumed to be...

  16. Time dependent rise and decay of photocurrent in zinc oxide nanoparticles in ambient and vacuum medium

    Science.gov (United States)

    C, Rajkumar; Srivastava, Rajneesh K.

    2018-05-01

    Zinc oxide (ZnO) nanoparticle has been synthesized by cost effective Co-precipitation method and studied its photo-response activity. The synthesized ZnO nanomaterial was characterized by using various analytical techniques such as x-ray diffraction (XRD), UV–visible spectroscopy, FTIR spectroscopy, photoluminescence (PL) spectroscopy, and Scanning Electron Microscopy (SEM). From the XRD results, it is confirmed that synthesized ZnO nanomaterial possess hexagonal wurtzite phase structure with an average crystallite size of ∼16–17 nm. The UV-Visible absorption spectrum shows that it has blue shift compared to their bulk counterparts. Photoluminescence spectra of ZnO nanoparticles have a strong violet band at 423 nm and three weak bands at 485 nm (blue), 506 nm (green), and 529 nm (green). The presence of hydroxyl group was confirmed by FTIR. The photo-response analysis was studied by the time-dependent rise and decay photocurrent of ZnO nanoparticle was tested in the air as well as vacuum medium.

  17. Plume rise predictions

    International Nuclear Information System (INIS)

    Briggs, G.A.

    1976-01-01

    Anyone involved with diffusion calculations becomes well aware of the strong dependence of maximum ground concentrations on the effective stack height, h/sub e/. For most conditions chi/sub max/ is approximately proportional to h/sub e/ -2 , as has been recognized at least since 1936 (Bosanquet and Pearson). Making allowance for the gradual decrease in the ratio of vertical to lateral diffusion at increasing heights, the exponent is slightly larger, say chi/sub max/ approximately h/sub e/ - 2 . 3 . In inversion breakup fumigation, the exponent is somewhat smaller; very crudely, chi/sub max/ approximately h/sub e/ -1 . 5 . In any case, for an elevated emission the dependence of chi/sub max/ on h/sub e/ is substantial. It is postulated that a really clever ignorant theoretician can disguise his ignorance with dimensionless constants. For most sources the effective stack height is considerably larger than the actual source height, h/sub s/. For instance, for power plants with no downwash problems, h/sub e/ is more than twice h/sub s/ whenever the wind is less than 10 m/sec, which is most of the time. This is unfortunate for anyone who has to predict ground concentrations, for he is likely to have to calculate the plume rise, Δh. Especially when using h/sub e/ = h/sub s/ + Δh instead of h/sub s/ may reduce chi/sub max/ by a factor of anywhere from 4 to infinity. Factors to be considered in making plume rise predictions are discussed

  18. Improvement in limit of detection in particle induced X-ray emission by means of rise time and pulse shape discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Papp, Tibor E-mail: tibpapp@netscape.nettibpapp@yahoo.ca; Lakatos, Tamas; Nejedly, Zdenek; Campbell, John L

    2002-04-01

    A digital signal processor, based upon high-rate sampling of the preamplifier output, and equipped with rise time and pulse shape discrimination, has been tested in three situations. This processor provided significant improvement of particle induced X-ray emission and X-ray fluorescence detection limits over the state of the art analog processors, depending on the energy and intensity distribution of the X-ray spectra. Additionally it had a superior performance when measurements were performed in an environment of large electronic noise and in large nuclear background environment. It has also improved the reduction of several artifacts in X-ray spectra.

  19. Methods of erection of high-rise buildings

    Directory of Open Access Journals (Sweden)

    Cherednichenko Nadezhda

    2018-01-01

    Full Text Available The article contains the factors determining the choice of methods for organizing the construction and production of construction and installation work for the construction of high-rise buildings. There are also indicated specific features of their underground parts, characterized by powerful slab-pile foundations, large volumes of earthworks, reinforced bases and foundations for assembly cranes. The work cycle is considered when using reinforced concrete, steel and combined skeletons of high-rise buildings; the areas of application of flow, separate and complex methods are being disclosed. The main conditions for the erection of high-rise buildings and their components are singled out: the choice of formwork systems, delivery and lifting of concrete mixes, installation of reinforcement, the formation of lifting and transporting and auxiliary equipment. The article prescribes the reserves of reduction in the duration of construction due to the creation of: complex mechanized technologies for the efficient construction of foundations in various soil conditions, including in the heaving, swelling, hindered, subsidence, bulk, water-saturated forms; complex mechanized technologies for the erection of monolithic reinforced concrete structures, taking into account the winter conditions of production and the use of mobile concrete-laying complexes and new generation machines; modular formwork systems, distinguished by their versatility, ease, simplicity in operation suitable for complex high-rise construction; more perfect methodology and the development of a set of progressive organizational and technological solutions that ensure a rational relationship between the processes of production and their maximum overlap in time and space.

  20. Sea-level rise risks to coastal cities

    Science.gov (United States)

    Nicholls, Robert J.

    2017-04-01

    Understanding the consequence of sea-level rise for coastal cities has long lead times and huge political implications. Civilisation has emerged and developed during a period of several thousand years during which in geological terms sea level has been unusually stable. We have now moved out of this period and the challenge will be to develop a long-term proactive assessment approach to manage this challenge. In 2005 there were 136 coastal cities with a population exceeding one million people and a collective population of 400 million people. All these coastal cities are threatened by flooding from the sea to varying degrees and these risks are increasing due to growing exposure (people and assets), rising sea levels due to climate change, and in some cities, significant coastal subsidence due to human agency (drainage and groundwater withdrawals from susceptible soils). In these cities we wish to avoid major flood events, with associated damage and potentially deaths and ultimately decline of the cities. Flood risks grow with sea-level rise as it raises extreme sea levels. As sea levels continue to rise, protection will have to be progressively upgraded. Even with this, the magnitude of losses when flood events do occur would increase as coastal cities expand, and water depths and hence unit damage increase with sea-level rise/subsidence. This makes it critical to also prepare for larger coastal flood disasters than we experience today and raises questions on the limits to adaptation. There is not an extensive literature or significant empirical information on the limits to adaptation in coastal cities. These limits are not predictable in a formal sense - while the rise in mean sea level raises the likelihood of a catastrophic flood, extreme events are what cause damage and trigger a response, be it abandonment, a defence upgrade or something else. There are several types of potential limits that could be categorised into three broad types: • Physical

  1. Temperature rise and stress induced by microcracks in accelerating structures

    Directory of Open Access Journals (Sweden)

    W. Zhu

    2010-12-01

    Full Text Available The temperature rise and induced stress due to Ohmic heating in the vicinity of microcracks on the walls of high-gradient accelerating structures are considered. The temperature rise and induced stress depend on the orientation of the crack with respect to the rf magnetic field, the shape of the crack, and the power and duration of the rf pulse. Under certain conditions the presence of cracks can double the temperature rise over that of a smooth surface. Stress at the bottom of the cracks can be several times larger than that of the case when there are no cracks. We study these effects both analytically and by computer simulation. It is shown that the stress in cracks is maximal when the crack depth is on the order of the thermal penetration depth.

  2. Influence of air flow parameters on nanosecond repetitively pulsed discharges in a pin-annular electrode configuration

    KAUST Repository

    Heitz, Sylvain A

    2016-03-16

    The effect of various air flow parameters on the plasma regimes of nanosecond repetitively pulsed (NRP) discharges is investigated at atmospheric pressure. The two electrodes are in a pin-annular configuration, transverse to the mean flow. The voltage pulses have amplitudes up to 15 kV, a duration of 10 ns and a repetition frequency ranging from 15 to 30 kHz. The NRP corona to NRP spark (C-S) regime transition and the NRP spark to NRP corona (S-C) regime transition are investigated for different steady and harmonically oscillating flows. First, the strong effect of a transverse flow on the C-S and S-C transitions, as reported in previous studies, is verified. Second, it is shown that the azimuthal flow imparted by a swirler does not affect the regime transition voltages. Finally, the influence of low frequency harmonic oscillations of the air flow, generated by a loudspeaker, is studied. A strong effect of frequency and amplitude of the incoming flow modulation on the NRP plasma regime is observed. Results are interpreted based on the cumulative effect of the NRP discharges and an analysis of the residence times of fluid particles in the inter-electrode region. © 2016 IOP Publishing Ltd.

  3. Influence of air flow parameters on nanosecond repetitively pulsed discharges in a pin-annular electrode configuration

    KAUST Repository

    Heitz, Sylvain A; Moeck, Jonas P; Schuller, Thierry; Veynante, Denis; Lacoste, Deanna

    2016-01-01

    The effect of various air flow parameters on the plasma regimes of nanosecond repetitively pulsed (NRP) discharges is investigated at atmospheric pressure. The two electrodes are in a pin-annular configuration, transverse to the mean flow. The voltage pulses have amplitudes up to 15 kV, a duration of 10 ns and a repetition frequency ranging from 15 to 30 kHz. The NRP corona to NRP spark (C-S) regime transition and the NRP spark to NRP corona (S-C) regime transition are investigated for different steady and harmonically oscillating flows. First, the strong effect of a transverse flow on the C-S and S-C transitions, as reported in previous studies, is verified. Second, it is shown that the azimuthal flow imparted by a swirler does not affect the regime transition voltages. Finally, the influence of low frequency harmonic oscillations of the air flow, generated by a loudspeaker, is studied. A strong effect of frequency and amplitude of the incoming flow modulation on the NRP plasma regime is observed. Results are interpreted based on the cumulative effect of the NRP discharges and an analysis of the residence times of fluid particles in the inter-electrode region. © 2016 IOP Publishing Ltd.

  4. Inertial rise of a meniscus on a vertical cylinder

    KAUST Repository

    O’ Kiely, Doireann; Whiteley, Jonathan P.; Oliver, James M.; Vella, Dominic

    2015-01-01

    © © 2015 Cambridge University PressA. We consider the inertia-dominated rise of a meniscus around a vertical circular cylinder. Previous experiments and scaling analysis suggest that the height of the meniscus, h-{m}, grows with the time following

  5. World medical schools: The sum also rises.

    Science.gov (United States)

    Rigby, Perry G; Gururaja, Ramnarayan P

    2017-06-01

    There is a worldwide shortage of doctors, which is true in most countries and on most continents. To enumerate the number of medical schools in the world at two different times, showing the trends and relating this to population is a beginning. The number is actually going up and has done so for some time; this has increased the supply of physicians and broadened healthcare delivery. The number to count for geographic and regional information about the medical schools relates directly to the supply of doctors. Regions were chosen from WHO and Foundation for the Advancement of International Medical Education and Research data to illustrate geographic distributions, physicians per patient and kinetics. The number of medical schools has consistently been rising around the world. However, world order is reverting to disorder, considering wars, disease and beleaguered stand-offs. None. Eight countries contain 40% of medical schools; however, several locations are rising faster than the rest. Some regions are stable, but sub-Saharan Africa, the Caribbean, South Asia and South America have increased the most in percentage recently, but not uniformly. Medical schools are related not only by geography, political boundaries and population but are concentrated in some regions. Graduate Medical Education positions appear to be short on a worldwide basis, as well as in some regions and countries. The number of medical schools is increasing worldwide and the identification of rapidly rising geographic areas is useful in exploring, planning and comparing regions. Controversy continues in a variety of locations, especially concerning Graduate Medical Education. In addition to funding, faculty candidates and accreditation, new schools are confronting a variety of choices in standards and quality, sizing and regional concerns.

  6. Time dependence of vacuum arc parameters

    International Nuclear Information System (INIS)

    Anders, A.; Anders, S.; Brown, I.G.

    1993-01-01

    Time-resolved investigations of the expanded plasma of vacuum arc cathode spots are described, including the study of the ion charge state distribution, the random cathode spot motion, and the crater formation. It was found that the ion charge state distribution changes over a time scale on the order of hundreds of microseconds. For the random spot motion two time scales were observed: a very short spot residence time of tens of nanoseconds which gives, combined with the step width, the diffusion parameter of the random motion, and a longer time scale on the order of 100 μs during which the diffusion parameter changes. Crater formation studies by scanning electron microscopy indicate the occurrence of larger craters at the end of crater chains. The existence of a time scale, much longer than the elementary times for crater formation and spot residence, can be explained by local heat accumulation

  7. Role of Off-Line-of-Sight Propagation in Geomagnetic EMP Formation

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, Hans W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-05-23

    The author’s synchrotron radiation based 3D geomagnetic EMP code MACSYNC has been used to explore the impact on pulse rise time and air conductivity of EMP propagation paths to the observer that are located off the direct line-of-sight (LOS) between gamma source and observer. This geometry is always present because, for an isotropic source, most the gammas are emitted at an angle with respect to the LOS. Computations for a 1 kt near-surface burst observed from space yield two principal findings: 1. The rise time is generated by the combined actions of a) electron spreading along the LOS due to the Compton electron emission angular distribution folded with electron multiple scattering effects, and b) radiation arrival time spreading due to length differences for different off-LOS propagation paths. The pulse rise time does not depend on the rise time of the conductivity. The conductivity rise time determines the pulse amplitude. 2. One-dimensional legacy EMP codes are inherently incapable of producing the correct pulse shape because they cannot treat the dependence of the conductivity on two dimensions, i.e. the radius from the source and the angle of the propagation path with the LOS. This divergence from one-dimensionality begins at a small fraction of a nanosecond for a sea-level burst. This effect will also be present in high-altitude bursts, however, determination of its onset time and magnitude requires high-altitude computations which have not yet been done.

  8. Comparison of GLONASS and GPS Time Transfers

    Science.gov (United States)

    Daly, P.; Koshelyaevsky, N. B.; Lewandowski, W.; Petit, G.; Thomas, C.

    1993-01-01

    The Russian global space navigation system GLONASS could provide a technique similar to GPS for international time comparison. The main limitation to its use for time transfer is the lack of commercially available time receivers. The University of Leeds built a GPS/GLONASS receiver five years ago and since then has provided continuous information about GLONASS time and its comparison with GPS time. For the last two years the VNIIFTRI and several other Russian time laboratories have used Russian-built GLONASS navigation receivers for time comparisons. Since June 1991, the VNIIFTRI has operated a GPS time receiver which offers, for the first time, an opportunity for the direct comparison of time transfers using GPS and GLONASS. This seven-month experiment shows that even with relatively imprecise data recording and processing, in terms of time metrology, GLONASS can provide continental time transfer at a level of several tens of nanoseconds.

  9. Present-day sea level rise: a synthesis

    International Nuclear Information System (INIS)

    Cazenave, A.; Llovel, W.; Lombard, A.

    2008-01-01

    Measuring sea level change and understanding its causes have improved considerably in the recent years, essentially because new in situ and remote sensing data sets have become available. Here we report on the current knowledge of present-day sea level change. We briefly present observational results on sea level change from satellite altimetry since 1993 and tide gauges for the past century. We next discuss recent progress made in quantifying the processes causing sea level change on time scales ranging from years to decades, i.e., thermal expansion, land ice mass loss and land water storage change. For the 1993-2003 decade, the sum of climate-related contributions agree well (within the error bars) with the altimetry-based sea level, half of the observed rate of rise being due to ocean thermal expansion, land ice plus land waters explaining the other half. Since about 2003, thermal expansion increase has stopped, whereas the sea level continues to rise, although at a reduced rate compared to the previous decade (2.5 mm/yr versus 3.1 mm/yr). Recent increases in glacier melting and ice mass loss from the ice sheets appear able to account alone for the rise in sea level reported over the last five years. (authors)

  10. Transient suppression of gap junctional intercellular communication after exposure to 100-nanosecond pulsed electric fields.

    Science.gov (United States)

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Hybrid integrated circuit for charge-to-time interval conversion

    Energy Technology Data Exchange (ETDEWEB)

    Basiladze, S.G.; Dotsenko, Yu.Yu.; Man' yakov, P.K.; Fedorchenko, S.N. (Joint Inst. for Nuclear Research, Dubna (USSR))

    The hybrid integrated circuit for charge-to time interval conversion with nanosecond input fast response is described. The circuit can be used in energy measuring channels, time-to-digital converters and in the modified variant in amplitude-to-digital converters. The converter described consists of a buffer amplifier, a linear transmission circuit, a direct current source and a unit of time interval separation. The buffer amplifier represents a current follower providing low input and high output resistances by the current feedback. It is concluded that the described converter excelled the QT100B circuit analogous to it in a number of parameters especially, in thermostability.

  12. On nuclear DD synthesis at the initial stage of nanosecond vacuum discharge with deuterium-loaded Pd anode

    Science.gov (United States)

    Kurilenkov, Yu K.; Gus'kov, S. Yu; Karpukhin, V. T.; Oginov, A. V.; Samoylov, I. S.

    2018-01-01

    Earlier, there was demonstrated generation of DD neutrons in an interelectrode medium of a low-energy (˜ 1 J) nanosecond vacuum discharge with a hollow cathode and a deuterium-loaded Pd anode. There was revealed essential role of formation of a virtual cathode and a potential well corresponding thereto in the processes of collisional DD synthesis in the interelectrode space. In this work, we have obtained as a result of an experiment and discussed the neutron yield at the very initial stage of the discharge, when the beam of auto-electrons just starts to irradiate the non-ideal surface of the deuterium-loaded Pd anode.

  13. Sub-nanosecond cinematography in laser fusion research: current techniques and applications at the Lawrence Livermore National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, L.W.

    1985-01-10

    Progress in laser fusion research has increased the need for detail and precision in the diagnosis of experiments. This has spawned the development and use of sophisticated sub-nanosecond resolution diagnostic systems. These systems typically use ultrafast x-ray or optical streak cameras in combination with spatially imaging or spectrally dispersing elements. These instruments provide high resolution data essential for understanding the processes occurring in the interaction of high intensity laser light with targets. Several of these types of instruments and their capabilities will be discussed. The utilization of these kinds of diagnostics systems on the nearly completed 100 kJ Nova laser facility will be described.

  14. Humidity Distributions in Multilayered Walls of High-rise Buildings

    Science.gov (United States)

    Gamayunova, Olga; Musorina, Tatiana; Ishkov, Alexander

    2018-03-01

    The limitation of free territories in large cities is the main reason for the active development of high-rise construction. Given the large-scale projects of high-rise buildings in recent years in Russia and abroad and their huge energy consumption, one of the fundamental principles in the design and reconstruction is the use of energy-efficient technologies. The main heat loss in buildings occurs through enclosing structures. However, not always the heat-resistant wall will be energy-efficient and dry at the same time (perhaps waterlogging). Temperature and humidity distributions in multilayer walls were studied in the paper, and the interrelation of other thermophysical characteristics was analyzed.

  15. Integrating wildfire plume rises within atmospheric transport models

    Science.gov (United States)

    Mallia, D. V.; Kochanski, A.; Wu, D.; Urbanski, S. P.; Krueger, S. K.; Lin, J. C.

    2016-12-01

    Wildfires can generate significant pyro-convection that is responsible for releasing pollutants, greenhouse gases, and trace species into the free troposphere, which are then transported a significant distance downwind from the fire. Oftentimes, atmospheric transport and chemistry models have a difficult time resolving the transport of smoke from these wildfires, primarily due to deficiencies in estimating the plume injection height, which has been highlighted in previous work as the most important aspect of simulating wildfire plume transport. As a result of the uncertainties associated with modeled wildfire plume rise, researchers face difficulties modeling the impacts of wildfire smoke on air quality and constraining fire emissions using inverse modeling techniques. Currently, several plume rise parameterizations exist that are able to determine the injection height of fire emissions; however, the success of these parameterizations has been mixed. With the advent of WRF-SFIRE, the wildfire plume rise and injection height can now be explicitly calculated using a fire spread model (SFIRE) that is dynamically linked with the atmosphere simulated by WRF. However, this model has only been tested on a limited basis due to computational costs. Here, we will test the performance of WRF-SFIRE in addition to several commonly adopted plume parameterizations (Freitas, Sofiev, and Briggs) for the 2013 Patch Springs (Utah) and 2012 Baker Canyon (Washington) fires, for both of which observations of plume rise heights are available. These plume rise techniques will then be incorporated within a Lagrangian atmospheric transport model (STILT) in order to simulate CO and CO2 concentrations during NASA's CARVE Earth Science Airborne Program over Alaska during the summer of 2012. Initial model results showed that STILT model simulations were unable to reproduce enhanced CO concentrations produced by Alaskan fires observed during 2012. Near-surface concentrations were drastically

  16. Development and application of sub-nanosecond pulse-repeatable hard X-ray source

    International Nuclear Information System (INIS)

    Quan Lin; Fan Yajun; Tu Jing

    2013-01-01

    A multipurpose X-ray source was developed to meet the needs of multitask application such as radiation detection, radiation imaging and so on. The multipurpose X-ray source has characteristic of adjustable width and energy, pulse-repetition operation, ultra-short pulse and fine stability. Its rising time is close to 98.6 ps, the operation voltage reaches 425 kV, and the peak fluence rate exceeds 2.07 × 10 18 cm -2 · s -1 at 10 cm, which provides an ideal radiation environment for relevant application. (authors)

  17. Porcine skin damage thresholds for pulsed nanosecond-scale laser exposure at 1064-nm

    Science.gov (United States)

    DeLisi, Michael P.; Peterson, Amanda M.; Noojin, Gary D.; Shingledecker, Aurora D.; Tijerina, Amanda J.; Boretsky, Adam R.; Schmidt, Morgan S.; Kumru, Semih S.; Thomas, Robert J.

    2018-02-01

    Pulsed high-energy lasers operating in the near-infrared (NIR) band are increasingly being used in medical, industrial, and military applications, but there are little available experimental data to characterize their hazardous effects on skin tissue. The current American National Standard for the Safe Use of Lasers (ANSI Z136.1-2014) defines the maximum permissible exposure (MPE) on the skin as either a single-pulse or total exposure time limit. This study determined the minimum visible lesion (MVL) damage thresholds in Yucatan miniature pig skin for the single-pulse case and several multiple-pulse cases over a wide range of pulse repetition frequencies (PRFs) (10, 125, 2,000, and 10,000 Hz) utilizing nanosecond-scale pulses (10 or 60 ns). The thresholds are expressed in terms of the median effective dose (ED50) based on varying individual pulse energy with other laser parameters held constant. The results confirm a decrease in MVL threshold as PRF increases for exposures with a constant number of pulses, while also noting a PRF-dependent change in the threshold as a function of the number of pulses. Furthermore, this study highlights a change in damage mechanism to the skin from melanin-mediated photomechanical events at high irradiance levels and few numbers of pulses to bulk tissue photothermal additivity at lower irradiance levels and greater numbers of pulses. The observed trends exceeded the existing exposure limits by an average factor of 9.1 in the photothermally-damaged cases and 3.6 in the photomechanicallydamaged cases.

  18. Nanosecond pulsed electric fields (nsPEFs) low cost generator design using power MOSFET and Cockcroft-Walton multiplier circuit as high voltage DC source

    International Nuclear Information System (INIS)

    Sulaeman, M. Y.; Widita, R.

    2014-01-01

    Purpose: Non-ionizing radiation therapy for cancer using pulsed electric field with high intensity field has become an interesting field new research topic. A new method using nanosecond pulsed electric fields (nsPEFs) offers a novel means to treat cancer. Not like the conventional electroporation, nsPEFs able to create nanopores in all membranes of the cell, including membrane in cell organelles, like mitochondria and nucleus. NsPEFs will promote cell death in several cell types, including cancer cell by apoptosis mechanism. NsPEFs will use pulse with intensity of electric field higher than conventional electroporation, between 20–100 kV/cm and with shorter duration of pulse than conventional electroporation. NsPEFs requires a generator to produce high voltage pulse and to achieve high intensity electric field with proper pulse width. However, manufacturing cost for creating generator that generates a high voltage with short duration for nsPEFs purposes is highly expensive. Hence, the aim of this research is to obtain the low cost generator design that is able to produce a high voltage pulse with nanosecond width and will be used for nsPEFs purposes. Method: Cockcroft-Walton multiplier circuit will boost the input of 220 volt AC into high voltage DC around 1500 volt and it will be combined by a series of power MOSFET as a fast switch to obtain a high voltage with nanosecond pulse width. The motivation using Cockcroft-Walton multiplier is to acquire a low-cost high voltage DC generator; it will use capacitors and diodes arranged like a step. Power MOSFET connected in series is used as voltage divider to share the high voltage in order not to damage them. Results: This design is expected to acquire a low-cost generator that can achieve the high voltage pulse in amount of −1.5 kV with falltime 3 ns and risetime 15 ns into a 50Ω load that will be used for nsPEFs purposes. Further detailed on the circuit design will be explained at presentation

  19. Timescales for detecting a significant acceleration in sea level rise.

    Science.gov (United States)

    Haigh, Ivan D; Wahl, Thomas; Rohling, Eelco J; Price, René M; Pattiaratchi, Charitha B; Calafat, Francisco M; Dangendorf, Sönke

    2014-04-14

    There is observational evidence that global sea level is rising and there is concern that the rate of rise will increase, significantly threatening coastal communities. However, considerable debate remains as to whether the rate of sea level rise is currently increasing and, if so, by how much. Here we provide new insights into sea level accelerations by applying the main methods that have been used previously to search for accelerations in historical data, to identify the timings (with uncertainties) at which accelerations might first be recognized in a statistically significant manner (if not apparent already) in sea level records that we have artificially extended to 2100. We find that the most important approach to earliest possible detection of a significant sea level acceleration lies in improved understanding (and subsequent removal) of interannual to multidecadal variability in sea level records.

  20. The use of the AOA TTR-4P GPS receiver in operation at the BIPM for real-time restitution of GPS time

    Science.gov (United States)

    Thomas, Claudine

    1994-01-01

    The Global Positioning System is an outstanding tool for the dissemination of time. Using mono-channel C/A-code GPS time receivers, the restitution of GPS time through the satellite constellation presents a peak-to-peak discrepancy of several tens of nanoseconds without SA but may be as high as several hundreds of nanoseconds with SA. As a consequence, civil users are more and more interested in implementing hardware and software methods for efficient restitution of GPS time, especially in the framework of the project of a real-time prediction of UTC (UTCp) which could be available in the form of time differences (UTCp - GPS time). Previous work, for improving the real-time restitution of GPS time with SA, to the level obtained without SA, focused on the implementation of a Kalman filter based on past data and updated at each new observation. An alternative solution relies upon the statistical features of the noise brought about by SA; it has already been shown that the SA noise is efficiently reduced by averaging data from numerous satellites observed simultaneously over a sufficiently long time. This method was successfully applied to data from a GPS time receiver, model AOA TTR-4P, connected to the cesium clock kept at the BIPM. This device, a multi-channel, dual frequency, P-code GPS time receiver, is one of the first TTR-4P units in operation in a civil laboratory. Preliminary comparative studies of this new equipment with conventional GPS time receivers are described in this paper. The results of an experimental restitution of GPS time, obtained in June 1993, are also detailed: 3 to 6 satellites were observed simultaneously with a sample interval of 15 s, an efficient smoothing of SA noise was realized by averaging data on all observed satellites over more than 1 hour. When the GPS system is complete in 1994, 8 satellites will be observable continuously from anywhere in the world and the same level of uncertainty will be obtained using a shorter averaging

  1. Rise, stagnation, and rise of Danish women's life expectancy

    DEFF Research Database (Denmark)

    Lindahl-Jacobsen, Rune; Rau, Roland; Jeune, Bernard

    2016-01-01

    Health conditions change from year to year, with a general tendency in many countries for improvement. These conditions also change from one birth cohort to another: some generations suffer more adverse events in childhood, smoke more heavily, eat poorer diets, etc., than generations born earlier...... favor forecasts that hinge on cohort differences. We use a combination of age decomposition and exchange of survival probabilities between countries to study the remarkable recent history of female life expectancy in Denmark, a saga of rising, stagnating, and now again rising lifespans. The gap between...... female life expectancy in Denmark vs. Sweden grew to 3.5 y in the period 1975-2000. When we assumed that Danish women born 1915-1945 had the same survival probabilities as Swedish women, the gap remained small and roughly constant. Hence, the lower Danish life expectancy is caused by these cohorts...

  2. Rising sea levels and small island states

    International Nuclear Information System (INIS)

    Leatherman, S.P.

    1994-01-01

    A review is given of the problems small island nations face with respect to sea level rise caused by global warming. Many small island nations are very vulnerable to sea level rise. Particularly at risk are coral reef atolls, which are generally quite small, lie within three metres of current sea levels, and have no land at higher elevations to relocate populations and economic activity. Volcanic islands in the Pacific have high ground, but it is largely rugged, high relief and soil-poor. The most vulnerable islands are those that consist entirely of atolls and reef islands, such as Kirabai, Maldives, Tokelau and Tuvalu. Small island states, which by themselves have little power or influence in world affairs, have banded together to form the Strategic Alliance of Small Island States (AOSIS). This alliance had grown to include 42 states by the time of the 1992 U.N. Earth Summit. Although the greenhouse effect is mainly caused by industrial nations, developing countries will suffer the most from it. Choices of response strategy will depend on environmental, economic and social factors. Most small island nations do not have the resources to fight sea level rise in the way that the Dutch have. Retreat can occur as a gradual process or as catastrophic abandonment. Prohibiting construction close to the water's edge is a good approach. Sea level histories for each island state should be compiled and updated, island geomorphology and settlement patterns should be surveyed to determine risk areas, storm regimes should be determined, and information on coastal impacts of sea level rise should be disseminated to the public

  3. Applications of nanosecond, kilojoule lasers to the basic physics of waves in plasmas

    International Nuclear Information System (INIS)

    Drake, R.P.

    1992-01-01

    Plasmas can sustain many normal modes of oscillation (waves), including both electromagnetic and electrostatic modes. These waves can interact by a wide variety of linear and nonlinear mechanisms, including mode coupling, mixing, and instabilities. Furthermore, such mechanisms compete, so that a given wave might be absorbed, might mode convert, or might decay by one of several instabilities, depending upon the specific circumstances in which it is produced. Moreover, such waves are important in many applications, including for example laser fusion, x-ray lasers, plasma accelerators, and ionospheric heating. Laser-produced plasmas can provide an effective medium for the studies of such waves and the related mechanisms. New opportunities will be made possible by the advent of comparatively inexpensive nanosecond, kilojoule lasers. One can now contemplate affordable experiments, not limited by programmatic constraints, that could study such the basic physics of the waves in such plasmas with unprecedented precision and in unprecedented detail

  4. Study on rapid evacuation in high-rise buildings

    Directory of Open Access Journals (Sweden)

    Xin Zhang

    2017-06-01

    Full Text Available More and more high rising buildings emerged in modern cities, but emergency evacuation of tall buildings has been a worldwide difficult problem. In this paper, a new evacuation device for high rising buildings in fire accident was proposed and studied. This device mainly consisted of special spiral slideway and shunt valve. People in this device could fast slide down to the first floor under gravity without any electric power and physical strength, which is suitable for various emergency evacuation including mobility-impaired persons. The plane simulation test has shown that human being in alternative clockwise and counterclockwise movement will not become dizzy. The evacuated people should wear protection pad, which can prevent slider from being injured by surface friction with the slide, and eliminate the friction coefficient difference caused by different clothes and slide surface. The calculation results show that the evacuation speed of the new device is much faster than traditional staircases. Moreover, such new evacuation device can also be used as a means of vertical transportation in high-rise buildings partly. People can take it from any floor to ground floor directly, which not only save time for waiting for the lifts but also save the power. The new evacuation system is of simple structure, easy to use, and suitable for evacuation and partly used as vertical downwards traffic, which shows light on solving world-wide difficulties on fast evacuation in high-rise buildings.

  5. Experimental researches on the single-bubble rising behavior in the water excited by oscillation

    International Nuclear Information System (INIS)

    Cai Jiejin; Zhong Minghuang; Wang Ke; Zeng Xixiang; Lin Yongcheng; WATANABE Tadashi

    2014-01-01

    This study try to carry out experiments to research the bubble rising behavior in the water excited by oscillation and focus on its dynamics characteristics under the oscillation condition with different oscillation frequencies and amplitudes, and get the relationship between bubble's characteristic parameter, such as the bubble shape, rising velocity, etc, and the influence parameters of time, oscillation frequencies, amplitudes, etc. The rising rule of the single bubble in the water excited by oscillation has been concluded. (authors)

  6. Very fast, high peak-power, planar triode amplifiers for driving optical gates

    International Nuclear Information System (INIS)

    Howland, M.M.; Davis, S.J.; Gagnon, W.L.

    1979-01-01

    Recent extensions of the peak power capabilities of planar triodes have made possible the latter's use as very fast pulse amplifiers, to drive optical gates within high-power Nd:glass laser chains. These pulse amplifiers switch voltages in the 20 kV range with rise times of a few nanoseconds, into crystal optical gates that are essentially capacitive loads. This paper describes a simplified procedure for designing these pulse amplifiers. It further outlines the use of bridged-T constant resistance networks to transform load capacitance into pure resistance, independent of frequency

  7. Study of laser-induced damage on the exit surface of silica components in the nanosecond regime in a multiple wavelengths configuration

    International Nuclear Information System (INIS)

    Chambonneau, Maxime

    2014-01-01

    In this thesis, laser-induced damage phenomenon on the surface of fused silica components is investigated in the nanosecond regime. This phenomenon consists in an irreversible modification of the material. In the nanosecond regime, laser damage is tightly correlated to the presence of non-detectable precursor defects which are a consequence of the synthesis and the polishing of the components. In this thesis, we investigate laser damage in a multiple wavelengths configuration. In order to better understand this phenomenon in these conditions of irradiation, three studies are conducted. The first one focuses on damage initiation. The results obtained in the single wavelength configurations highlight a coupling in the multiple wavelengths one. A comparison between the experiments and a model developed during this thesis enables us to improve the knowledge of the fundamental processes involved during this damage phase. Then, we show that post mortem characterizations of damage morphology coupled to an accurate metrology allow us to understand both the nature and also the chronology of the physical mechanisms involved during damage formation. The proposed theoretical scenario is confirmed through various experiments. Finally, we study damage growth in both the single and the multiple wavelengths cases. Once again, this last configuration highlights a coupling between the wavelengths. We show the necessity to account for the spatial characteristics of the laser beams during a growth session. (author) [fr

  8. Timing performance of ZnO:Ga nanopowder composite scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Turtos, Rosana M. [Universita degli Studi di Milano-Bicocca, Milano (Italy); Gundacker, Stefan; Lucchini, Marco T.; Lecoq, Paul; Auffray, Etiennette [CERN, Geneva (Switzerland); Prochazkova, Lenka; Cuba, Vaclav [Czech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Prague (Czech Republic); Buresova, Hana [Nuvia a.s, Kralupy nad Vltavou (Czech Republic); Mrazek, Jan [Institute of Photonics and Electronics AS CR, Prague (Czech Republic); Nikl, Martin [Institute of Physics of the AS CR, Prague (Czech Republic)

    2016-11-15

    The implementation of nanocrystal-based composite scintillators as a new generation of ultrafast particle detectors is explored using ZnO:Ga nanopowder. Samples are characterized with a spectral-time resolved photon counting system and pulsed X-rays, followed by coincidence time resolution (CTR) measurements under 511 keV gamma excitation. Results are comparable to CTR values obtained using bulk inorganic scintillators. Bringing the ZnO:Ga nanocrystal's timing performance to radiation detectors could pave the research path towards sub-20 ps time resolution as shown in this contribution. However, an efficiency boost when placing nanopowders in a transparent host constitutes the main challenge in order to benefit from sub-nanosecond recombination times. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Timing and mechanism of the rise of the Shillong Plateau in the Himalayan foreland.

    OpenAIRE

    Govin, Gwladys; Najman, Yanina Manya Rachel; Copley, Alex; Millar, Ian; Van der Beek, Peter; Huyghe, Pascale; Grujic, Djordje; Davenport, Jesse

    2018-01-01

    The Shillong Plateau (northeastern India) constitutes the only significant topography in the Himalayan foreland. Knowledge of its surface uplift history is key to understanding topographic development and unraveling tectonic–climate–topographic coupling in the eastern Himalaya. We use the sedimentary record of the Himalayan foreland basin north of the Shillong Plateau to show that the paleo-Brahmaputra river was redirected north and west by the rising plateau at 5.2–4.9 Ma. We suggest that on...

  10. High-efficiency VCSEL arrays for illumination and sensing in consumer applications

    Science.gov (United States)

    Seurin, Jean-Francois; Zhou, Delai; Xu, Guoyang; Miglo, Alexander; Li, Daizong; Chen, Tong; Guo, Baiming; Ghosh, Chuni

    2016-03-01

    There has been increased interest in vertical-cavity surface-emitting lasers (VCSELs) for illumination and sensing in the consumer market, especially for 3D sensing ("gesture recognition") and 3D image capture. For these applications, the typical wavelength range of interest is 830~950nm and power levels vary from a few milli-Watts to several Watts. The devices are operated in short pulse mode (a few nano-seconds) with fast rise and fall times for time-of-flight applications (ToF), or in CW/quasi-CW for structured light applications. In VCSELs, the narrow spectrum and its low temperature dependence allows the use of narrower filters and therefore better signal-to-noise performance, especially for outdoor applications. In portable devices (mobile devices, wearable devices, laptops etc.) the size of the illumination module (VCSEL and optics) is a primary consideration. VCSELs offer a unique benefit compared to other laser sources in that they are "surface-mountable" and can be easily integrated along with other electronics components on a printed circuit board (PCB). A critical concern is the power-conversion efficiency (PCE) of the illumination source operating at high temperatures (>50 deg C). We report on various VCSEL based devices and diffuser-integrated modules with high efficiency at high temperatures. Over 40% PCE was achieved in broad temperature range of 0-70 °C for either low power single devices or high power VCSEL arrays, with sub- nano-second rise and fall time. These high power VCSEL arrays show excellent reliability, with extracted mean-time-to-failure (MTTF) of over 500 years at 60 °C ambient temperature and 8W peak output.

  11. Ablation of (GeS{sub 2}){sub 0.3}(Sb{sub 2}S{sub 3}){sub 0.7} glass with an ultra-violet nano-second laser

    Energy Technology Data Exchange (ETDEWEB)

    Knotek, P., E-mail: petr.knotek@upce.cz [University of Pardubice, Faculty of Chemical Technology, Joint Laboratory of Solid State Chemistry of IMC and University of Pardubice, Studentska 573, 532 10 Pardubice (Czech Republic); University of Pardubice, Faculty of Chemical Technology, Department of General and Inorganic Chemistry, Studentska 573, 532 10 Pardubice (Czech Republic); Navesnik, J.; Cernohorsky, T. [University of Pardubice, Faculty of Chemical Technology, Institute of Environmental and Chemical Engineering, Studentska 573, 532 10 Pardubice (Czech Republic); Kincl, M.; Vlcek, M.; Tichy, L. [Institute of Macromolecular Chemistry, AS CR, Heyrovskeho sq. 2, 162 06 Prague (Czech Republic)

    2015-04-15

    Highlights: • The interaction of (GeS{sub 2}){sub 0.3}(Sb{sub 2}S{sub 3}){sub 0.7} bulk glass and film with UV nanosecond laser. • Ablation process, topography of crater and structure of the material were studied. • Ablation threshold fluencies changed with the spot diameter and number of pulses. • The photo-thermal expansion of the material occurred for low laser fluency. • Laser direct writing process applicable for fabrication of passive optical elements. - Abstract: The results of an experimental study of the laser ablation of bulk and thin films of a GeSbS chalcogenide glass using UV nanosecond pulses are reported. The response of the samples to illumination conditions was studied through the use of atomic force spectroscopy, digital holographic microscopy, Raman scattering and scanning electron microscopy. The multi-pulse ablation thresholds were determined for both the bulk and thin film samples for varying number of pulses and illuminated spot diameter. The possible application of direct laser writing into the bulk and thin films of this material is presented.

  12. Second-order contributions to relativistic time delay in the parametrized post-Newtonian formalism

    International Nuclear Information System (INIS)

    Richter, G.W.; Matzner, R.A.

    1983-01-01

    Using a parametrized expansion of the solar metric to second order in the Newtonian potential, we calculate the relativistic delay in the round-trip travel time of a radar signal reflected from a nearby planet. We find that one second-order contribution to the delay is on the order of ten nanoseconds, which is comparable to the uncertainties in present-day experiments involving the Viking spacecraft

  13. Population dynamics of Hawaiian seabird colonies vulnerable to sea-level rise

    Science.gov (United States)

    Hatfield, Jeff S.; Reynolds, Michelle H.; Seavy, Nathaniel E.; Krause, Crystal M.

    2012-01-01

    Globally, seabirds are vulnerable to anthropogenic threats both at sea and on land. Seabirds typically nest colonially and show strong fidelity to natal colonies, and such colonies on low-lying islands may be threatened by sea-level rise. We used French Frigate Shoals, the largest atoll in the Hawaiian Archipelago, as a case study to explore the population dynamics of seabird colonies and the potential effects sea-level rise may have on these rookeries. We compiled historic observations, a 30-year time series of seabird population abundance, lidar-derived elevations, and aerial imagery of all the islands of French Frigate Shoals. To estimate the population dynamics of 8 species of breeding seabirds on Tern Island from 1980 to 2009, we used a Gompertz model with a Bayesian approach to infer population growth rates, density dependence, process variation, and observation error. All species increased in abundance, in a pattern that provided evidence of density dependence. Great Frigatebirds (Fregata minor), Masked Boobies (Sula dactylatra), Red-tailed Tropicbirds (Phaethon rubricauda), Spectacled Terns (Onychoprion lunatus), and White Terns (Gygis alba) are likely at carrying capacity. Density dependence may exacerbate the effects of sea-level rise on seabirds because populations near carrying capacity on an island will be more negatively affected than populations with room for growth. We projected 12% of French Frigate Shoals will be inundated if sea level rises 1 m and 28% if sea level rises 2 m. Spectacled Terns and shrub-nesting species are especially vulnerable to sea-level rise, but seawalls and habitat restoration may mitigate the effects of sea-level rise. Losses of seabird nesting habitat may be substantial in the Hawaiian Islands by 2100 if sea levels rise 2 m. Restoration of higher-elevation seabird colonies represent a more enduring conservation solution for Pacific seabirds.

  14. Sun Radio Interferometer Space Experiment (SunRISE)

    Science.gov (United States)

    Kasper, Justin C.; SunRISE Team

    2018-06-01

    The Sun Radio Interferometer Space Experiment (SunRISE) is a NASA Heliophysics Explorer Mission of Opportunity currently in Phase A. SunRISE is a constellation of spacecraft flying in a 10-km diameter formation and operating as the first imaging radio interferometer in space. The purpose of SunRISE is to reveal critical aspects of solar energetic particle (SEP) acceleration at coronal mass ejections (CMEs) and transport into space by making the first spatially resolved observations of coherent Type II and III radio bursts produced by electrons accelerated at CMEs or released from flares. SunRISE will focus on solar Decametric-Hectometric (DH, 0.1 space before major SEP events, but cannot be seen on Earth due to ionospheric absorption. This talk will describe SunRISE objectives and implementation. Presented on behalf of the entire SunRISE team.

  15. FDTD simulation of exposure of biological material to electromagnetic nanopulses

    Energy Technology Data Exchange (ETDEWEB)

    Simicevic, Neven [Center for Applied Physics Studies, Louisiana Tech University, Ruston, LA 71272 (United States); Haynie, Donald T [Center for Applied Physics Studies and Biomedical Engineering, Louisiana Tech University, Ruston, LA 71272 (United States)

    2005-01-21

    Ultra-wideband (UWB) electromagnetic pulses of nanosecond duration, or nanopulses, are of considerable interest to the communications industry and are being explored for various applications in biotechnology and medicine. The propagation of a nanopulse through biological matter has been computed using the finite difference-time domain (FDTD) method. The approach required the reparametrization of existing Cole-Cole model-based descriptions of dielectric properties of biological matter in terms of the Debye model without loss of accuracy. Several tissue types have been considered. Results show that the electromagnetic field inside biological tissue depends on incident pulse rise time and width. Rise time dominates pulse behaviour inside tissue as conductivity increases. It has also been found that the amount of energy deposited by 20 kV m{sup -1} nanopulses is insufficient to change the temperature of the exposed material for pulse repetition rates of 1 MHz or less, consistent with recent experimental results.

  16. Rise of a cold plume

    International Nuclear Information System (INIS)

    Kakuta, Michio

    1977-06-01

    The rise of smoke from the stacks of two research reactors in normal operation was measured by photogrametric method. The temperature of effluent gas is less than 20 0 C higher than that of the ambient air (heat emission of the order 10 4 cal s -1 ), and the efflux velocity divided by the wind speed is between 0.5 and 2.8 in all 16 smoke runs. The field data obtained within downwind distance of 150m are compared with those by plume rise formulas presently available. Considering the shape of bending-over plume, the Briggs' formula for 'jet' gives a reasonable explanation of the observed plume rise. (auth.)

  17. RADIOMETRIC CALIBRATION OF MARS HiRISE HIGH RESOLUTION IMAGERY BASED ON FPGA

    Directory of Open Access Journals (Sweden)

    Y. Hou

    2016-06-01

    Full Text Available Due to the large data amount of HiRISE imagery, traditional radiometric calibration method is not able to meet the fast processing requirements. To solve this problem, a radiometric calibration system of HiRISE imagery based on field program gate array (FPGA is designed. The montage gap between two channels caused by gray inconsistency is removed through histogram matching. The calibration system is composed of FPGA and DSP, which makes full use of the parallel processing ability of FPGA and fast computation as well as flexible control characteristic of DSP. Experimental results show that the designed system consumes less hardware resources and the real-time processing ability of radiometric calibration of HiRISE imagery is improved.

  18. A two-level model of rise time in quantum cascade laser materials applied to 5 micron, 9 micron and terahertz-range wavelengths

    International Nuclear Information System (INIS)

    Webb, J F; Yong, K S C; Haldar, M K

    2014-01-01

    An equivalent circuit simulation of a two-level rate equation model for quantum cascade laser (QCL) materials is used to study the turn on delay and rise time for three QCLs with 5 micron, 9 micron and terahertz-range wavelengths. In order to do this it is necessary that the model can deal with large signal responses and not be restricted to small signal responses; the model used here is capable of this. The effect of varying some of the characteristic times in the model is also investigated. The comparison of the terahertz wave QCL with the others is particularly important given the increased interest in terahertz sources which have a large range of important applications, such as in medical imaging

  19. Measurements of Electric Field in a Nanosecond Pulse Discharge by 4-WAVE Mixing

    Science.gov (United States)

    Baratte, Edmond; Adamovich, Igor V.; Simeni Simeni, Marien; Frederickson, Kraig

    2017-06-01

    Picosecond four-wave mixing is used to measure temporally and Picosecond four-wave mixing is used to measure temporally and spatially resolved electric field in a nanosecond pulse dielectric discharge sustained in room air and in an atmospheric pressure hydrogen diffusion flame. Measurements of the electric field, and more precisely the reduced electric field (E/N) in the plasma is critical for determination rate coefficients of electron impact processes in the plasma, as well as for quantifying energy partition in the electric discharge among different molecular energy modes. The four-wave mixing measurements are performed using a collinear phase matching geometry, with nitrogen used as the probe species, at temporal resolution of about 2 ns . Absolute calibration is performed by measurement of a known electrostatic electric field. In the present experiments, the discharge is sustained between two stainless steel plate electrodes, each placed in a quartz sleeve, which greatly improves plasma uniformity. Our previous measurements of electric field in a nanosecond pulse dielectric barrier discharge by picosecond 4-wave mixing have been done in air at room temperature, in a discharge sustained between a razor edge high-voltage electrode and a plane grounded electrode (a quartz plate or a layer of distilled water). Electric field measurements in a flame, which is a high-temperature environment, are more challenging because the four-wave mixing signal is proportional to the to square root of the difference betwen the populations of N2 ground vibrational level (v=0) and first excited vibrational level (v=1). At high temperatures, the total number density is reduced, thus reducing absolute vibrational level populations of N2. Also, the signal is reduced further due to a wider distribution of N2 molecules over multiple rotational levels at higher temperatures, while the present four-wave mixing diagnostics is using spectrally narrow output of a ps laser and a high

  20. Time-Resolved Soft X-ray Diffraction Reveals Transient Structural Distortions of Ternary Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Klaus Mann

    2009-11-01

    Full Text Available Home-based soft X-ray time-resolved scattering experiments with nanosecond time resolution (10 ns and nanometer spatial resolution were carried out at a table top soft X-ray plasma source (2.2–5.2 nm. The investigated system was the lyotropic liquid crystal C16E7/paraffin/glycerol/formamide/IR 5. Usually, major changes in physical, chemical, and/or optical properties of the sample occur as a result of structural changes and shrinking morphology. Here, these effects occur as a consequence of the energy absorption in the sample upon optical laser excitation in the IR regime. The liquid crystal shows changes in the structural response within few hundred nanoseconds showing a time decay of 182 ns. A decrease of the Bragg peak diffracted intensity of 30% and a coherent macroscopic movement of the Bragg reflection are found as a response to the optical pump. The Bragg reflection movement is established to be isotropic and diffusion controlled (1 μs. Structural processes are analyzed in the Patterson analysis framework of the time-varying diffraction peaks revealing that the inter-lamellar distance increases by 2.7 Å resulting in an elongation of the coherently expanding lamella crystallite. The present studies emphasize the possibility of applying TR-SXRD techniques for studying the mechanical dynamics of nanosystems.