International Nuclear Information System (INIS)

The possibility to compress and to split laser pulses at their nonlinear optical transmission through semiconductor films was investigated

International Nuclear Information System (INIS)

Full text: In the upper layers of the Earth's atmosphere, molecular nitrogen absorbs the extreme ultraviolet (XUV) solar radiation. The absorption is associated with dipole-allowed excitation of states of singlet ungerade symmetry ("1#SIGMA#"+_u and "1#PI#_u), which are known to undergo predissociation due to coupling with a mainfold of "1#PI#_u states. We determined new N_2 isotopic lifetimes of many "1#SIGMA#"+_u and "1#PI#_u states via line broadening measurements in the frequency domain. Ultrahigh resolution XUV + UV ionization spectra were recorded (bandwidth #approx# 250 MHz, resolving power 10"7), from which the natural linewidth, i.e. lifetime, was determined. These lifetimes provide new information about the predissociation of the singlet ungerade states in N_2. Tunable narrowband XUV radiation was produced by successively pulsed amplification of cw dye laser radiation, frequency doubling the ...

Energy Technology Data Exchange (ETDEWEB)

A design of a compact free-electron laser (FEL), generating ultra-fast, high-peak flux, XUV pulses is presented. The FEL is driven by ahigh-current, 0.5 GeV electron beam from the Lawrence Berkeley National Laboratory (LBNL) laser-plasma accelerator, whose active acceleration length is only a few centimeters. The proposed ultra-fast source (~;;10 fs) would be intrinsically temporally synchronized to the drive laser pulse, enabling pump-probe studies in ultra-fast science. Owing to the high current (>10 kA) of the laser-plasma-accelerated electron beams, saturated output fluxes are potentially greater than 10^13 photons/pulse. Devices based both on self-amplified spontaneous emission and high-harmonic generated input seeds, to reduce undulator length and fluctuations, are considered.

International Nuclear Information System (INIS)

There is growing interest in the generation and characterization of femtosecond and subfemtosecond pulses from linac-based free-electron lasers (FELs). In this report, following the method of Ricci and Smith (Phys. Rev. ST Accel. Beams 3, 032801 (2000)), we investigate the measurement of the longitudinal bunch profile of an ultrashort electron bunch produced by these FELs. We show that this method can be applied in a straightforward manner at x-ray FEL facilities such as the Linac Coherent Light Source by slightly adjusting the second bunch compressor followed by running the bunch on an rf zero-crossing phase of the final linac. We find that the linac wakefield strongly perturbs the measurement, and through analysis show that it can be compensated in a simple way. We demonstrate the effectiveness of this method and wakefield compensation through numerical simulations, including effects of coherent synchrotron radiation and longitudinal space ...

Energy Technology Data Exchange (ETDEWEB)

Detecting a camouflaged target in a visually noisy background depends on the ability of the observer to discriminate the target from the surrounding terrain. Visible laser irradiation at less than damage levels can act as a masking source by compromising or reducing the observer's ability to resolve differences in the visual scene. Previous research has examined this concept by investigating laser flash effects on: acuity (size discrimination); tracking (motion discrimination); visual sensitivity (color); and contrast sensitivity functions (luminance contrast). In all cases, flashes from continuous-wave (CW) sources have proven more effective visually than pulsed (Q-switched) sources, when compared on peak-energy criteria (i.e., MPE), even though Q-switched lasers induce damage at lower energy doses. Additionally, the inherent safety of ultra-short laser pulses has been questioned. Past animal research has shown ...

Energy Technology Data Exchange (ETDEWEB)

Since 1979, scientists and engineers at the Los Alamos National Laboratory have designed, constructed, and operated a radio-frequency (RF) linac free-electron laser (FEL) at wavelengths from 9 to 45 /mu/m. Coupled with success of other research centers investigating wavelengths from the visible to far-infrared, Los Alamos is now proposing a vacuum-ultraviolet and soft x-ray (referred to henceforth as extreme ultraviolet, (XUV)) FEL oscillator/Self-Amplified Spontaneous Emission amplifier with beam energies ranging from 100 MeV to 1 GeV. This paper will focus on the first milestone of the proposed Los Alamos XUV project, i.e., a 250-MeV linac with approximately 50 mA of average current, producing photons with wavelengths below 1000 /angstrom/. 3 refs., 3 figs.

British Library Electronic Table of Contents (United Kingdom)

AbstractPurpose: To implement and examine the feasibility of a three-dimensional (3D) ultrashort TE (UTE) sequence on a 7 Tesla (T) clinical MR scanner in comparison with 3T MRI at high isotropic resolution. Materials and Methods: Using an in-house built saddle coil at both field strengths we have imaged mid-diaphysial sections of five fresh cadaveric specimens of the distal tibia. An additional in vivo scan was performed at 7 Tesla using a quadrature knee coil. Results: Using the same type of saddle coil at both field strengths, a significant increase in SNR at 7T compared with 3T (factor 1.7) was found. Significantly shorter T2* values were found at the higher field strength (T2* = 552.2 126 s at 7T versus T2* = 1163 391 s at 3T). Conclusion: UHF MRI at 7T has great potential for imaging...

Science.gov (United States)

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Science.gov (United States)

The purpose of this project is to demonstrate targeted infill and extension drilling opportunities, better determinations of oil-in-place, methods for improved completion efficiency and the suitability of waterflooding in certain shallow-shelf carbonate reservoirs in the Williston Basin, Montana, North Dakota and South Dakota. Improved reservoir characterization utilizing 3-dimensional and multi-component seismic area is being investigated for identification of structural and stratigraphic reservoir compartments. These seismic characterization tools are integrated with geological and engineering studies. Improved completion efficiency is being tested with extended-reach jetting lance and other ultra-short radius lateral technologies. Improved completion efficiency, additional wells at closer spacing and better estimates of oil-in-place will result in additional oil production by primary and enhanced recovery processes.

Energy Technology Data Exchange (ETDEWEB)

Specificity of the pulses mean frequency measurement (the pulses being generated in a stochastic process) is described. Status of the domain of analog frequency meters is presented. Methods of increasing accuracy of such meters are discussed.

Science.gov (United States)

A univibrator and a pulse height discriminator using tunnel diodes and backward diodes are described, along with their applications in pulse shaping and fast coincidence technique. The main advantages achieved are simplicity of design and speed. The characteristics of the two diodes are shown. (auth)

CERN Document Server

Development of High Field Dipole and High Current Pulse Power Supply for Compact Proton Synchrotron

Science.gov (United States)

A Pulsed Radiation Dosimetry System designed to measure radiation produced by particle accelerators is described. The problems associated with total-dose measurement of irregular shaped pulses of ionizing radiation have been simplified. The system responds to extremely narrow pulses of charged particles or X-rays using a pin diode as the detector. Direct readout of dose in rads (Si) is displayed on a 3-1/2 digit digital panel meter. The system will operate in either the multiple-pulse or single-pulse mode. The multiple-pulse mode would be useful in monitoring or tuning a linear accelerator. In the single-pulse mode the system will automatically display total dose of a transient event in real time and hold that measurement indefinitely or until the next measurement is made. The system features an automatic reset in either mode.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

KoreaScience (Korea)

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KoreaScience (Korea)

Full Text Available

KoreaScience (Korea)

Full Text Available

Science.gov (United States)

The purpose of this project is to demonstrate targeted infill and extension drilling opportunities, better determinations of oil-in- place, methods for improved completion efficiency and the suitability of waterflooding in certain shallow-shelf carbonate reservoirs in the Williston Basin, Montana, North Dakota and South Dakota. Improved reservoir characterization utilizing 3-dimensional and multi-component seismic area is being investigated for identification of structural and stratigraphic reservoir compartments. These seismic characterization tools are integrated with geological and engineering studies. Improved completion efficiency is being tested with extended- reach jetting lance and other ultra-short radius lateral technologies. Improved completion efficiency, additional wells at closer spacings better estimates of oil-in-place will result in additional oil production by primary and enhanced recovery processes. Technical progress is described for field ...

International Nuclear Information System (INIS)

The influence of the main factors on device efficiency of pulsed liquid jet pump with gas-liquid piston is analysed, the theoretical equation and its time-averaged solution of pulsed liquid jet pump device efficiency are derived. The theoretical and experimental results show that the efficiency of transmission of energy and mass to use pulsed jet is greatly raised, compared with steady jet, in the same device of liquid jet pump. The calculating results of time-averaged efficiency of pulsed liquid jet pump are approximately in agreement with the experimental results in our and foreign countries

Energy Technology Data Exchange (ETDEWEB)

Relativistic electron beams are used for generating high power microwaves. These microwave sources require electron beam generators spanning significant ranges in voltage and impedance. The pulsed power technology used to generate these electron beams is presented. Electron beam generators that produce beams with pulse durations in the 10-ns to 100-ns regime consist of an energy-storage section, pulse-shaping section, and an electron beam diode. The energy-storage section is either a Marx generator or capacitor bank-pulsed transformer. The pulse shaping is done with high-voltage transmission lines. The electron beam diode is usually a cold-cathode, space-charge-limited flow device. For longer pulses (/approximately/1 ..mu..s) the energy storage and pulse chaping can be combined. Lumped-element pulse-forming networks ...

International Nuclear Information System (INIS)

The time and dose characteristics of the electron and X-ray radiations of a tube, connected to a subnanosecond mega volt accelerator, are measured. By the pulse of the accelerating voltage of #>=# 600 kV with duration of #approx =# 0.3 ns the tube generates approximately 5 x 10"1"2 electrons pulse. The current amplitude equals approximately 5 kA/pulse and the radiation dose-about 5 kGy/pulse. The X-ray radiation dose from the tantalum external target constitutes 0.15 Gy/pulse. The prototypes of the electron and X-ray tubes sufficiently lower volumes, opening new applications in the technique and medicine, are developed

Energy Technology Data Exchange (ETDEWEB)

In the process of backward Raman amplification (BRA), the leading layers of the seed laser pulse can shadow the rear layers, thus weakening the effective seeding power and affecting parameters of output pulses in BRA. We study this effect numerically and also analytically by approximating the pumped pulse by the ''*-pulse'' manifold of self-similar solutions. We determine how the pumped pulse projection moves within the *-pulse manifold, and describe quantitatively the effective seeding power evolution. Our results extend the quantitative theory of BRA to regimes where the effective seeding power varies substantially during the amplification. These results might be of broader interest, since the basic equations, are general equations for resonant 3-wave interactions.

Energy Technology Data Exchange (ETDEWEB)

An electronically controllable apparatus is described which modulates a continuous wave laser beam so as to produce an output beam consisting of coherent ''pulses'' that are electronically controllable as to both pulse repetition rate and pulse width. The apparatus includes two acoustic devices positioned so that the laser beam passes through them in sequence, and apparatus or for passing sound waves through the devices to frequency shift the laser radiation as well as to diffract it. Each acoustic device such as generates sound waves containing a group of frequencies which result in spaced pulses. The spreading of a laser beam at which emanates from the first acoustic device is countered by the second acoustic device to produce a collimated, coherently pulsed, laser beam.

International Nuclear Information System (INIS)

A system for real-time neutron radiography of moving objects is described. It comprise a source adapted to generate a continuous uninterrupted series of neutron pulses. Each pulse has a predetermined peak power and duration compatible with the framing times of a real-time video imaging system. A transporter moves an object to be examined to bring sequentially position selected portions of the object in the path of the pulses. Where the object itself has moving components, pulses are sequentially incident on the object. According to any dissimilarities, the object will alter the intensity of the neutrons passing therethrough. In order to record separately the changes in the neutron intensity, for each pulse, an imager is positioned to receive the neutron beam pulses which have been altered by their passage through the object and produce images indicating ...

International Nuclear Information System (INIS)

We have studied both theoretically and experimentally a new scheme of active pulse compression in a free electron laser (FEL) amplifier. The pulse compression scheme presented here is the following. A frequency-chirped pulse is injected into the FEL interaction region. Because of the high gain and narrow bandwidth of the FEL interaction, only the resonant frequency band of the pulse is actively amplified, resulting in a short pulse of high power coherent radiation at the output of the laser. For our experimental parameters (beam voltage #approx =# 150 kV, current #approx =# 5.0 A, wiggler period #approx =# 3.5 cm and gain #approx =# 10 dB), pulses of a few nanoseconds were generated at #approx =# 10 GHz after an interaction length of 2.30 m, in good agreement with theoretical expectations. For the same input pulses (width > 100 ns, ...

International Nuclear Information System (INIS)

We report coupling and guiding of pulses of peak power up to 0.3 TW in 1.5 cm long preformed plasma waveguides generated in a high repetition rate argon gas jet. Coupling of up to 52% was measured for 50 mJ, -110 fs pulses injected at times longer than 20 ns, giving guided intensities up to -5x1016 W/cm2. It was found that for short delays between waveguide generation and pulse injection, pulse shortening occurred, with this effect reduced as delay was increased. Injection into the waveguide of two consecutive pulses separated by a few nanoseconds resulted in the reduction of shortening of the second pulse at all delays. Femtosecond time-resolved shadowgrams of the coupling of injected pulses into the waveguide show that there is ?0.5 mm of neutral gas remaining at the waveguide entrance after waveguide generation.

Energy Technology Data Exchange (ETDEWEB)

A system is claimed for multiplexing or demultiplexing pulsed laser radiation having an acousto-optical device which is electrically controlled to switch a common path of high pulse rate laser radiation between a plurality of spatially distinct paths for relatively lower pulse rate laser radiation at which the pulses are sequenced according to a predetermined time pattern. The acousto-optical element typically includes a Bragg cell which is electrically driven by a set of distinct frequencies, causing deflection of radiation passing therethrough at a predetermined set of angles whereby pulsed radiation on a single path may be distributed onto the plural separate paths or radiation on plural separate paths of time-sequenced pulses of radiation can be combined into a single path of augmented pulse rate. The control of the acousto-optical ...

Science.gov (United States)

... The Effect of the Temperature to Which the Material is Heated on the Process of Formation of Intermetallic Compounds in Magnetic Pulse Welding,. ...

Science.gov (United States)

A line-to-plate reactor was set-up in the experimental study on the application of nanosecond pulsed corona discharge plasma technology in environmental pollution control. Investigation on the attenuation and distortion of the amplitude of the pulse wave front and the discharge image as well as the waveform along the corona wire was conducted. The results show that the wave front decreases sharply during the corona discharge along the corona wire. The higher the amplitude of the applied pulse is, the more the amplitude of the wave front decreased. The wave attenuation responds in a lower corona discharge inversely. To get a higher efficiency of the line-to-plate reactor a sharp attenuation of the corona has to be considered in practical design.

CERN Document Server

We propose using large Air Cerenkov Telescopes (ACT's) to search for optical, pulsed signals from extra-terrestrial intelligence. Such dishes collect tens of photons from a nanosecond-scale pulse of isotropic equivalent power of tens of solar luminosities at a distance of 100 pc. The field of view for giant ACT's can be on the order of ten square degrees, and they will be able to monitor 10 to 10$^2$ stars simultaneously for nanosecond pulses of about 6th mag or brighter. Using the Earth's diameter as a baseline, orbital motion of the planet could be detected by timing the pulse arrival times.

International Nuclear Information System (INIS)

... beam monitoring betatrons delay circuits errors fluctuations gamma radiation

Science.gov (United States)

Not Available

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

In terms of the kinetic theory of the interaction between the high-power short-time laser pulses with plasma based on the propagator plotting for the plasma particle distribution functions one studied the generation of the hot electrons and of the fast ions as the relativistic femtosecond laser pulses travelled through the supercritical density plasma. One performed calculations based on the various values of the laser pulse intensity, types of the multiple-charged ions, the plasma inhomogeneity degree. One studied the acceleration mechanisms both of the plasma electrons and ions

KoreaScience (Korea)

Full Text Available

Science.gov (United States)

... 1 ..... 14 High Dielectric Constant Ceramics for Use in Blumlein Transmission Lines ..... 14 ...

International Nuclear Information System (INIS)

We report on a time-resolved measurement of self-amplified spontaneous emission free-electron laser (FEL) pulses. We observed that the spikes in such FEL pulses have an intrinsic positive chirp and the energy chirp in the electron bunch mapped directly into the FEL output. The measurement also provides rich information on the statistics of the FEL pulses.

DEFF Research Database (Denmark)

We present a monolithic, self-starting, all-PM, stabilized Yb-fiber laser, pulse-compressed in a hollow-core PM photonic crystal fiber, providing the 370 fs pulses of 4 nJ energy with high mode quality.

International Nuclear Information System (INIS)

Among the investigations conducted on the space shuttle flight STS 3 March 1982 was an experiment in which a 1-keV, 100-mA electron gun was pulsed at 3.25 and 4.87 kHz. The resultant waves were measured with a broadband plasma wave receiver. At the time of flight the experimental setup was unique in that the electron beam was square wave modulated and that the shuttle offered relatively long times for in situ measurements of the ionospheric plasma response to the VLF pulsing sequences. In addition to electromagnetic response at the pulsing frequencies the waves exhibited various spectral harmonics as well as the unexpected occurrence of satellite lines around those harmonics. Both phenomena occurred with a variety of different characteristics for different pulsing sequences.

Energy Technology Data Exchange (ETDEWEB)

The detection of explosives is a notoriously difficult problem, especially at stand-off distances, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring optimal dynamic detection to exploit the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity of explosives signatures while reducing the influence of noise and the signals from background interferents in the field (increase selectivity). These goals are being addressed by operating in an optimal nonlinear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked control and probe ...

CERN Document Server

Calculations relating to two experiments that demonstrate coherent control of preformed rubidium-85 molecules in a magneto-optical trap using ultrafast laser pulses are presented. In the first experiment, it is shown that pre-associated molecules in an incoherent mixture of states can be made to oscillate coherently using a single ultrafast pulse. A novel mechanism that can transfer molecular population to more deeply bound vibrational levels is used in the second. Optimal parameters of the control pulse are presented for the application of the mechanism to molecules in a magneto-optical trap. The calculations make use of an experimental determination of the initial state of molecules photoassociated by the trapping lasers in the magneto-optical trap and use shaped pulses consistent with a standard ultrafast laser system.

International Nuclear Information System (INIS)

The advances in laser technology have made available very short and intense laser pulses which can be used to seed a high-gain single-pass free-electron laser (FEL) amplifier. With these seed pulses, a regime of the FEL interaction where the radiation evolution is simultaneously dominated by nonlinear effects (saturation) and time-dependent effects (slippage) can be explored. This regime is characterized by the propagation of a solitary wavelike pulse where the power of the optical wave grows quadratically with time, its pulse length decreases and the spectral bandwidth increases. We analyze the interplay between the field and particle dynamics of this propagation regime which was studied before and termed super-radiance. Furthermore we analyze the properties of the strong higher-order harmonic emission from this wave and its behavior when propagating in a cascade FEL. The super-radiant ...

Energy Technology Data Exchange (ETDEWEB)

The authors investigated the application of pulsed corona discharge process to the removal of SO{sub 2} and NO{sub x} from industrial flue gas of an ioron-ore sintering plant. This study was performed on a pilot scale, which is the most advanced demonstration of this process. The flow rate of 5000 m{sup 3}/h of the flue gas was successfully treated. The electrode structure of the corona reactor is the same with that of conventional electrostatic precipitator. The authors made use of magnetic pulse compression technology to produce repetitive high voltage pulse. Pulse width (full width at half maximum) was reduced to less than 1 {micro}s by connecting a resister in parallel with the corona reactor. An inductor was added to the resister in series to minimize the loss by restricting the current flowing through the resister. By this way, they were able to deliver pulse power with peak ...

International Nuclear Information System (INIS)

A high power Free-Electron Laser (FEL) has lased at a wavelength of 22 #mu#m at the Japan Atomic Energy Research Institute (JAERI). The maximum power on a macro-pulse average is 1.7 kW, and it corresponds to an FEL energy of 160 #mu#J/micro-pulse. Extraction efficiency from the electron beam to the FEL radiation was measured to be 5.3% by an energy analyzer, when the maximum FEL power was coupled out. The rms wavelength spread was measured to be 4.6% at the same time. The extraction efficiency, in general, has a maximum value near the zero detuning length of an optical cavity, where (in contrast) the single-pass gain becomes smallest. A high peak current and a long macro-pulse duration are therefore indispensable for realizing high efficiency. The electron beam energy is 16.5 MeV, and the average current is 5.3 mA at a micro-pulse repetition rate of 10.4 MHz. The macro-pulse ...

Energy Technology Data Exchange (ETDEWEB)

The US Department of Energy's Pittsburgh Energy Technology Center (PETC) is actively pursuing the development and testing of coal-fired combustion systems for residential, commercial, and industrial market sectors. In response, MTCI initiated the development of a new combustor technology based on the principle of pulse combustion under the sponsorship of PETC (Contract No. AC22-83PC60419). The initial pulse combustor development program was conducted in three phases (MTCI, Development of a Pulsed Coal Combustor Fired with CWM, Phase III Final Report, DOE Contract No. AC22-83PC60419, November 1986). Phase I included a review of the prior art in the area of pulse combustion and the development of pulse combustor design concepts. It led to the conclusion that pulse combustors offer technical and base-of-operation advantages over conventional burners and ...

Energy Technology Data Exchange (ETDEWEB)

A self-seeded free electron laser (FEL) provides a high gain and extraction efficiency for the emitted light. An accelerator outputs a beam of electron pulses to a permanent magnet wiggler having an input end for receiving the electron pulses and an output end for outputting light and the electron pulses. An optical feedback loop collects low power light in a small signal gain regime at the output end of said wiggler and returns the low power light to the input end of the wiggler while outputting high power light in a high signal gain regime.

International Nuclear Information System (INIS)

Measurements of low-energy (#approx#10"- "1"0 J) femtosecond laser pulse durations have been carried out on the basis of second-order autocorrelation function analysis. The scheme of non collinear second harmonic generation realized in KDP crystal has been used for increasing of the measurement contrast and accuracy. Proposed scheme can be used for measurements in wide enough ranges of laser pulse durations (from tens femto seconds to hundreds picoseconds) and energies. (authors)

Energy Technology Data Exchange (ETDEWEB)

There is increasing demand to functionalize meso- and nano-porous materials by coating and make the porous substrate biocompatible or environment friendly. However, coating on a meso-porous substrate poses great challenges, especially if the pore aspect ratio is high. In the current work the pulsed laser deposition (PLD) method is used for coating Ni{sub 3}Al-based meso-porous membranes with diamond-like carbon (DLC) layers of high thickness homogeneity and adhesion. (orig.)

Energy Technology Data Exchange (ETDEWEB)

A small, permanent-magnet insert structure for the removal of electrons from pulsed, extracted, negative ion beams has been developed at Lawrence Berkeley National Laboratory. The device was computer modeled and designed for an extraction field strength of 3 kV/mm. The testing was carried out with a rf driven multicusp ion source optimized for the production of H{sup {minus}} ions and pulsed at a few Hz with pulse widths of several hundreds of {mu}s. It is demonstrated that the insert structure together with a collar can remove over 98{percent} of electrons from the extracted H{sup {minus}} ion beam without any significant deterioration of the H{sup {minus}} ion output. Application to other negative ion beams can be expected from this magnetic collar insert. {copyright} {ital 1996 American Institute of Physics.}

Science.gov (United States)

... at compositions below -AlP 4 the films were still unstable, hydrolysing in room air, and the long term stability of higher aluminium phosphides is in ...

International Nuclear Information System (INIS)

This study was the analyse the relationship between properties of ion nitrided Fe sintered material and parameters of plasma nitriding process. Pure fe sintered materials (relative density : 92%) were fabricated by hot-pressing and nitrided under pulsed DC plasma for 4 hours. The large number of parameters in plasma diffusion treatment allows close control of the process so that surface layers with defined microstructures and properties can be obtained. The number of micropores in nitriding layer can be reduced in pulsed DC plasma by reducing the plasma power and by varying the gas mixture. The phase constitution of compound layer of nitrided Fe sintered material were influenced by gas mixture (N_2 : H_2) and pulsed ratio (pulse on/off time ratio).

Energy Technology Data Exchange (ETDEWEB)

To measure electron reactions on a picosecond timescale the investigators developed a picosecond pulse-conductivity technique, which makes use of the electron fine-structure pulses of our LINAC (pulse width 25 vs FWHM) to produce excess electrons and now detects changes in sample conductance under optimum conditions with an instrumental response of 18 ps. This resolution is in agreement with a theoretical estimate. This technique has been successfully applied to study excess electron reactions in solvents covering a mobility range from 0.24 to 100 cm/sup 2/V/sup -1/s/sup -1/; extension to lower mobility liquids seem possible.

Energy Technology Data Exchange (ETDEWEB)

A flowing carbon dioxide laser was operated at low pressures up to 4 torr. Excitation of the laser was provided using various combinations of direct current (DC), pulsed microwave, and continuous wave (CW) microwave excitation. The microwaves were in the 2.45 GHz band and were coupled into the gas using a slow-wave interdigital transmission line. Laser output of 25 milliwatts (mw) was achieved using a DC discharge only. A combination of a DC discharge and pulsed microwaves doubled the output and resulted in some modulation. Changing the laser gas mixture and pulsed microwave field characteristics allowed some flexibility in the modulation. Lasing was not achieved with excitation from the CW microwaves alone due to the formation of localized discharges. Using pulsed microwaves to sustain the discharge and CW microwaves to pump the laser, a quasi-CW output of 55 mw was achieved.

International Nuclear Information System (INIS)

Presented are the investigation results of electrophysical and physico-mechanical properties of KLF-20, Viksint U-4-21, Viksint KT-73, UF-7-21, KG-184, KL-4, KL-16SE-305, VIAT-1 and PPK-21 sealants, irradiated with sources of continuous and pulse #gamma#-radiation, as well as pulse #gamma#-neutron radiation. It is shown that electrophysical and physico-mechanical properties of sealants after irradiation by continuous #gamma#-radiation up to 10"6 doses and pulse gamma-neutron radiation with neutron fluence of 10"1"3 neutron/cm"2 and #gamma#-radiation dose of 10"4R do not practically change. Electric conductivity and tangent of the angle of dielectric losses increase in the process of irradiation. Electric conductivity depends on irradiation type, is proportional to dose rate and does not depend on temperature and pulse duration.

Energy Technology Data Exchange (ETDEWEB)

In the rf-driven free-electron laser (FEL) at the Los Alamos National Laboratory, there are two pulsed-power rf modulators as sources for two tandem, side-coupled 20-MeV linear accelerators. The rf power used to control the cavity fields is supplied by two 5.5-MW modulating anode klystrons operating at a center frequency of 1300.2 MHz. The modulation of the 125 kV klystron is achieved by using a triode switch tube that provides a pulse width up to 300 ..mu..s and a pulse repetition rate up to 10 Hz. This paper describes the present configuration of these two duplicate systems and presents plans for meeting the requirements of future rf FEL experiments at Los Alamos. 12 refs., 5 figs.

Energy Technology Data Exchange (ETDEWEB)

We present preliminary analysis for the feasibility of the attosecond x-ray pulses at a proposed FERMI@ELETTRA free electron laser (FEL) [1]. In part 1 we restrict ourselves to minimal modifications to the proposed FEL and consider a scheme for attosecond x-ray production which can be qualified as a small add-on to a primary facility. We demonstrate that at 5-nm wavelength our scheme is capable for production of pulses with an approximate duration of 100 attoseconds at approximately 2 MW peak power and with an absolute temporal synchronization to a pump laser pulse. In part 2 we propose to use an FEL amplifier seeded by a VUV signal and to follow it by the scheme for attosecond x-ray production described in part 1.

Science.gov (United States)

Electrically triggered action potentials in the giant alga Chara corallina are associated with a transient rise in the concentration of free Ca2+ in the cytoplasm (Ca2+cyt). The present measurements of Ca2+cyt during membrane excitation show that stimulating pulses of low magnitude (subthreshold pulse) had no perceivable effect on Ca2+cyt. When the strength of a pulse exceeded a narrow threshold (suprathreshold pulse) it evoked the full extent of the Ca2+cyt elevation. This suggests an all-or-none mechanism for Ca2+ mobilization. A transient calcium rise could also be induced by one subthreshold pulse if it was after another subthreshold pulse of the same kind after a suitable interval, i.e., not closer than a few 100 ms and not longer than a few seconds. This dependency of Ca2+ mobilization on single and double pulses can be simulated by a ...

Science.gov (United States)

on this technology has beenproposedas a payload on SpaceStation Freedom to be launched in the near future [1]. Direct detection 4-ary pulse position modula- ...

Science.gov (United States)

... The three meteorological rocket systems, in order of ... IC3 and IC4 divides the incoming clock pulses f ... at the junction of the temperature sensor and R ...

International Nuclear Information System (INIS)

The heating and current drive systems are being developed to support long pulse, high #beta#, advanced tokamak fusion physics experiments in the KSTAR tokamak. The heating and current drive systems consisting of neutral beam injection (NBI), ion cyclotron waves (ICRF), lower hybrid waves (LHCD) and electron cyclotron waves (ECH/ECCD) have been designed to operate for pulse lengths up to 300 sec and to provide a range of control functions including current drive and profile control. Development of key technologies for high power, long pulse operation has been on going. Substantial progress has been made on areas such as RF launchers, ion source, and high power supplies.

Energy Technology Data Exchange (ETDEWEB)

Effects of 2450-MHz circularly polarized microwave irradiation on central nervous system functions were studied. Pulsed (microsecond, 500 pps) microwaves decreased high-affinity sodium-dependent choline uptake in the hippocampus and frontal cortex of the rat. The effect on hippocampal choline uptake was blocked by pretreatment with narcotic antagonists. Continuous-wave microwaves of the same power density decreased choline uptake in the frontal cortex only. Furthermore, it was found that the effects of pulsed microwaves on central cholinergic activity are classically conditionable to cues in the exposure environment. The hypothesis that some of the neurological effects of pulsed microwave irradiation are caused by its effect on the auditory system was investigated. Effects of pink noise and pulsed microwaves were compared.

Energy Technology Data Exchange (ETDEWEB)

During a Workshop on Gamma-Gamma Colliders in Lawrence Berkeley Laboratory, it was pointed out that an 1-{mu}m laser that can produce 1-J, 1-ps pulses at a few hundred hertz is required. With high-power scalability and ease of formatting, an FEL can be a promising candidate for such a laser. The authors propose an FEL scheme based on chirped-pulsed regenerative amplification to achieve this high peak-power laser. The 1-ps pulse of a solid-state laser will be stretched, amplified, and recompressed to achieve the high peak power. The system is relatively simple and consists of mostly components that have already been demonstrated. This paper will describe the proposal and the important issues of such a scheme.

International Nuclear Information System (INIS)

The detection efficiency of a lithium glass detector was calculated using MCNP code, and the calculation was compared with the published results in Pulsed Sphere Plan. A lithium glass detector of our own was made, and its neutron efficiency was calculated. The calculated neutron efficiency was verified with both pulsed and steady DD neutrons. Characteristics of Neutron response of "6Li detector was discussed. (authors)

CERN Document Server

We discuss optimal detection of fast radio transients from astrophysical objects while taking into account the effects of propagation through intervening ionized media, including dispersion, scattering and scintillation.Our analysis applies to the giant-pulse phenomenon exhibited by some pulsars, for which we show examples, and to radio pulses from other astrophysical sources, such as prompt radio emission from gamma-ray burst sources and modulated signals from extra-terrestrial civilizations.

International Nuclear Information System (INIS)

The author is exploring the efficiency of pulsed plasma processing in the removal of nitrogen dioxide, nitrogen oxide, and other pollutants. This process uses an electrical discharge to create chemical radicals from air molecules. These radicals can react with pollutants and form harmless compounds. Additives such as hydrocarbons are also used to improve the efficiency of the removal. The efficient removal of nitrogen dioxide has required the presence of dilute aqueous solution of ammonia.

International Nuclear Information System (INIS)

This paper summarizes a method to evaluate the possible effects of magnetohydrodynamic-electromagnetic pulse (MHD-EMP) on power systems. This method is based on the approach adapted to study the impact of geomagnetic storms on power systems. The paper highlights the similarities and differences between the two phenomena. Also presented are areas of concern which are anticipated from MHD-EMP on the overall system operation. 12 refs., 1 fig.

Energy Technology Data Exchange (ETDEWEB)

Operation at ITER specifications of the Kamaboko III ion source for 1000 second pulses of deuterium negative ion beams is underway on the MANTIS test stand. Efficient production of negative ions at low arc power requires injection of cesium into the source, temperature control of the plasma grid, and a period of conditioning of several days. Two different concepts of temperature regulated plasma grids are currently being tested. (author)

Energy Technology Data Exchange (ETDEWEB)

Free-electron-laser (FEL) oscillators require a train of high-brightness bunches. Conventional subharmonic bunchers are currently used with rf linacs to generate pulse trains, but the resulting dilution of the transverse phase space and lower beam brightness are unacceptable for high-performance FELs. Recent developments suggest that photoemitters of high quantum efficiency combined with rapid acceleration can produce pulse trains of higher brightness than has been achieved before.

International Nuclear Information System (INIS)

Isotopically selective IR multiphoton dissociation of molecules (SF_6, CF_3I) in a pulsed gas-dynamic flow interacting with a solid surface was studied for the first time. A noticeable (severalfold) increase in the yield of products (compared to excitation of molecules in an unperturbed flow) without a substantial decrease in the selectivity of the process was observed. Possible reasons for the effect are discussed. (laser applications and other topics in quantum electronics)

Energy Technology Data Exchange (ETDEWEB)

We have developed a novel insulator concept that involves the use of alternating layers of conductors and insulators with periods less than 1 mm. We have demonstrated that these structures perform 2 to 5 times better than conventional insulators in long pulse, short pulse, and alternating polarity applications. We present new testing results showing exceptional behavior at DC, with gradients in excess of 110kV/cm in vacuum.

Energy Technology Data Exchange (ETDEWEB)

Implementation of quantum logical gates for multilevel systems is demonstrated through decoherence control under the quantum adiabatic method using simple phase modulated laser pulses. We make use of selective population inversion and Hamiltonian evolution with time to achieve such goals robustly instead of the standard unitary transformation language. (letter to the editor)

Energy Technology Data Exchange (ETDEWEB)

The interaction of intense, sub-picosecond laser pulses with solid targets produces intense picosecond x-ray pulses. With focused laser pulses of several 10 {sup 18} W/cm{sup 2}, He-like and H-like line radiation from targets such as aluminum and silicon has been produced. The energy conversion efficiency from the laser pulse energy to the 1--2 keV line x-rays is nearly one percent. The duration of the line x-ray radiation is of the order of ten picoseconds, although this may be an upper estimate because of the temporal resolution of the x-ray streak camera. The spatial extent of the x-ray source region is only slightly larger than the laser focal spot, or about 10 {mu}m in diameter. With these characteristics, such x-ray sources emit an intensity of nearly 10{sup 14} W/cm{sup 2}. Experiments and modeling which led to the above conclusions will be discussed.

Science.gov (United States)

We present computer modeling along with experimental data on the formation of sharp conical tips on silicon-based three-layer structures that consist of a single-crystal Si layer on a 1 {mu}m layer of silica on a bulk Si substrate. The upper Si layers with thicknesses in the range of 0.8-4.1 {mu}m were irradiated by single pulses from a KrF excimer laser focused onto a spot several micrometers in diameter. The computer simulation includes two-dimensional time-dependent heat transfer and phase transformations in Si films that result from the laser irradiation (the Stefan problem). After the laser pulse, the molten material self-cools and resolidifies, forming a sharp conical structure, the height of which can exceed 1 {mu}m depending on the irradiation conditions. We also performed computer simulations for experiments involving single-pulse irradiation of bulk silicon, reported by other groups. We discuss conditions under ...

International Nuclear Information System (INIS)

This work aims at improving the understanding of the dynamics of a Free Electron Laser (FEL) based on a storage ring. A new phenomenon of saturation by the electron bunch transverse dimensions is pointed out, during the FEL operation with a magnetic optics ''low emittance''. A part of this thesis work concerns the study of the longitudinal dynamics of the FEL depending on a parameter: the detuning between the pass frequency of the electrons and the back and return frequency of the laser pulse in the optical cavity. This study shows that the FEL presents a pulsed or a steady state behavior depending on the detuning. Besides, a spectro-temporal behavior of the FEL is pointed out showing the FEL pulse substructures and holes in the spectrum. Another part of this work concerns the response of the resonant FEL system, when a perturbation is applied on the gain. Under the effect of a modulation, the FEL can present a periodic or ...

CERN Document Server

Up to now the long range filaments have been considered as a balance between Kerr focusing and defocusing by plasma generation in the nonlinear focus. However, it is difficult to apply the above explanation of filamentation in far-field zone. There are basically two main characteristics which remain the same at these distances - the super broad spectrum and the width of the core, while the power in a stable filament drops to the critical value for self-focusing. At such power the plasma and higher-order Kerr terms are too small to prevent self-focusing. We suggest here a new mechanism for stable soliton pulse propagation in far-away zone, where the power of the laser pulse is slightly above the critical one, and the pulse comprises super-broad spectra. For such pulses the diffraction is not paraxial and an initially symmetric Gaussian pulse takes parabolic form at several ...

British Library Electronic Table of Contents (United Kingdom)

Pulses are rich in nutrients. The existence of anti-nutritional components and the length of time required for preparation have, however, limited their frequency of use compared to recommended intake levels. Anti-nutritional components in pulses can be largely removed by heat treatment. Additionally pre-treatment of pulses with heat and processing of seeds into flour could further enhance their use by decreasing processing and preparation times. In this study, trypsin inhibitor activity, functional properties, and microstructural characteristics of flours prepared from different varieties of lentil, chickpea, and pea as affected by roasting and boiling were evaluated. Both thermal treatments resulted in significant reduction (p<0.05) in trypsin inhibitor activity ranging from -95.6% to -37...

Energy Technology Data Exchange (ETDEWEB)

The production of retrograde amnesia (RA) upon electron-beam exposure was investigated. RA production was evaluated using a single-trial avoidance task for 10, 1, and 0.1 microsecond pulsed exposures. The dose-response curve obtained at each pulse duration showed significant RA production. The most effective dose range was 0.1-10 rad at a dose rate of 1,000,000 rad/sec. By employing a 10 rad (1,000,000 rad/s) pulse, a memory loss of the events occurring in the previous 4 sec was demonstrated. The conclusion was that the RA effect might be due to sensory system activation which provided a novel stimulus that masked previous stimuli.

Energy Technology Data Exchange (ETDEWEB)

The Pulsed Lepton Source (PLS) project opens some exciting possibilities for muon and neutrino physics . The PLS would use the 0.25 4s proton pulses from the upgraded Proton Storage Ring (PSR) at LAMPF to create short, intense bursts of muons and neutrinos. The neutrino beam would be used for a few fundamentally important weak interaction physics experiments. The muon beams would find a wide variety of applications in both fundamental and applied'' muon physics areas. After a brief discussion of the physical layouts of the PSR and the proposed PLS in Sec. 2 and muon area in Sec. 3, we note some of the muon physics experiments and areas that could advantageously be addressed at the PLS in Secs. 4 and 5, and conclude in Sec. 6.

International Nuclear Information System (INIS)

Conductive TiN/Si_3N_4 ceramic composites were processed by electrical discharge machining (EDM) and their microstructure and conductivity were investigated. The whole process of tool electrode wear is evaluated by sinker-EDM. The machined surfaces of TiN/Si_3N_4 ceramic composites were examined by scanning electron microscopy (SEM) and profilometry to determine the surface finish. The electrode wear rate of brass is higher than copper electrode for all EDMed tests. The surface texture was found to have greater dependence on pulse energy. It was observed that the sinker-EDM at higher pulse energy caused severe microdamage in the surface. The surface roughness (Ra) values also increase with increasing pulse energy.

CERN Document Server

The nature of the `inner engine' that accelerate and collimate the relativistic flow at the cores of GRBs is the most interesting current puzzle concerning GRBs. Numerical simulations have shown that the internal shocks' light curve reflects the activity of this inner engine. Using a simple analytic toy model we clarify the relations between the observed $ \\gamma $-rays light curve and the inner engine's activity and the dependence of the light curves on the inner engine's parameters. This simple model also explains the observed similarity between the observed distributions of pulses widths and the intervals between pulses and the correlation between the width of a pulse and the length of the preceding interval. Our analysis suggests that the variability in the wind's Lorentz factors arises due to a modulation of the mass injected into a constant energy flow.

Energy Technology Data Exchange (ETDEWEB)

One of the more extensive uses of directional drilling anywhere in the world has been in the development of the East Wilmington Oil Field in Long Beach, California. The Measurement-While-Drilling (MWD) directional system has been tested on several wells and proven to provide the required accuracy, along with many advantages over past methods, used in the field development. Accurate transmission by MWD of bottom-hole measurements to the surface is provided by mud pressure pulses generated in the drill pipe downhole and detected by a pressure transducer includes the means for detecting, recording and processing these pressure pulses, to translate the information from the pressure pulses to rig floor displays usable by the drilling crew. 2 refs.

Science.gov (United States)

A voice activated garage door opener was designed for a handicapped person to open a garage door without assistance. This design uses speech recognition of one word. The activating word that was chosen is "up". The frequency spectrum of "up" was captured on a soundboard and is the basis of this design. Filters are used to pick out three frequency bands in this spectrum. The output signals from these filters are then compared to three threshold voltages using voltage comparators. If the output signals from the filters are above the threshold voltages, the comparators go high. Monostable multivibrators are used on the output of the comparators to lengthen the high pulses. When all of the pulses from the monostable multivibrators are high at the same time, an AND gate output goes high. This high pulse activates the door opener. PMID:8329601

Energy Technology Data Exchange (ETDEWEB)

This paper describes the specifications, conceptual design, prototype testing and operating experience of an oil-filled high voltage pulse transmission cable adapted from commercially available air-dielectric RF components. Lawrence Livermore National Laboratory's Advanced Test Accelerator (ATA) requires a method of transmitting 250kV, 70 nanosecond pulses from the power conditioning equipment to the accelerator. The oil-filled cable approach was chosen over alternative concepts because of its high voltage holding capacity, long life and flexibility. The criteria for cable and connector design are discussed. The results of prototype testing and performance of the final design are presented.

International Nuclear Information System (INIS)

One of the main challenges for a high energy #gamma##gamma# collider is the high repetition rate required for the laser-electron-beam collisions to convert into high energy gamma beams. State-of-the-art, high power lasers have a much lower repetition rate than that of the electron pulses. It is therefore highly desirable that the same laser pulse can be reused. As an example, for NLC where beams collide at 120 Hz, within each collision cycle there are 90 electron bunches separated by 1.4 ns between successive bunches. We show, by invoking a recently invented laser optical box, that the laser pulses can be reused for the entire train of bunches within each collision cycle. ((orig.)).

Science.gov (United States)

Haemangiomas usually develop within the first few weeks of life, most regressing spontaneously before the age of 7 years. Some may ulcerate or compromise a vital function, in which case systemic corticosteroids, surgery or radiotherapy may be helpful. All of these treatment modalities are associated with significant morbidity. Treatment with the 585 nm flashlamp pulsed dye laser is safe and effective in the management of superficial vascular malformations. We report seven patients, under 12 months of age, who presented with proliferative haemangiomas, causing functional impairment. Ulcerated lesions were present in four patients. The patients were treated with the 585 nm pulsed dye laser (fluences 7.0-9.25 J/cm2), at intervals of 4-8 weeks. All of the lesions showed a significant reduction in size, together with improvement in the colour and integrity of the overlying skin. Treatment with the 585 nm pulsed dye laser should ...

UK PubMed Central (United Kingdom)

Analysis of the pulsed-field gel electrophoretic profiles of 82 pneumococcal isolates with reduced susceptibility to ciprofloxacin (RSC) and of 90 co-occurring susceptible isolates indicates a considerable...Full Text Available

International Nuclear Information System (INIS)

The automatic real-time system operating at the LU-10 linac and providing measurements of the parameters such as the beam current (average and pulse values), the electron energy, the linear density distribution of beam current, and also the conveyor speed is described in the paper.

Science.gov (United States)

Technologies for materials, processes, and manufacturing that will provide safe, .... advanced energy conversion techniques, and pulsed inductive and ... duration antimatter storage and transportation, and methods for utilizing ...... EVA systems can be found in the EVA Technology Roadmap of the EVA Project Plan. ...

Energy Technology Data Exchange (ETDEWEB)

The traveling-wave mode in ring lasers is achieved by two methods: by a reversing mirror, and by using an intracavity nonreciprocal device. This paper is devoted to realization of the traveling-wave mode in a mode-locked YAG-Nd ring laser by a method proposed by Tomov et al. This method uses two intracavity Q-switches. In mode-locked operation, pulses are generated that can be considered short compared with the period of modulation T = L/C (where L is the length of the perimeter of the cavity). Analysis shows that if the shift of the switching signals corresponds to the time of travel of a light pulse between Q-switches, the pulse in one direction will pass the Q-switches at instants of zero losses, while losses in the other direction will be maximized for a distance between Q-switches of L/4, and will be zero for a distance L/2. Experimental verification of the proposed method gave unidirectional lasing with an intensity ...

Energy Technology Data Exchange (ETDEWEB)

A case of {beta}-thalassemia intermedia with spinal cord compression due to extramedullary hematopoiesis, which was successfully treated by blood transfusion, is presented. Emphasis was made on the MRI appearance of extramedullary hematopoiesis on different pulse sequences. The theories that aimed to explain the involvement of the epidural space by extramedullary hematopoiesis are discussed.

International Nuclear Information System (INIS)

The major activities of the various Institute's departments are highlighted. The following departments are included: (i) Tokamak; (ii) Pulse plasma systems; (iii) Thermal plasma; (iv) Materials engineering; (v) Laser plasma; and (vi) Optical diagnosis. (P.A.)

UK PubMed Central (United Kingdom)

The use of dendritic cells (DCs) as a cellular adjuvant is a promising approach to the immunotherapy of cancer. It has previously been demonstrated that DCs pulsed ex vivo with Toxoplasma gondii...Full Text Available

UK PubMed Central (United Kingdom)

Naturally occurring and contaminant ferromagnetic and ferrimagnetic particles have been found within or near cells, and might allow pulsed magnetic fields to create transient cell membrane opening ("pores")....Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The longitudinal and transverse dynamics of a heavy ion fusion beam during the drift compression and final focus phase is studied. A lattice design with four time-dependent magnets is described that focuses the entire beam pulse onto a single focal point with the same spot size.

UK PubMed Central (United Kingdom)

Normal reproductive functioning may require secretion of LH independently of FSH. Variation in GnRH pulse frequency and inhibin negative feedback are mechanisms for differential gonadotropin regulation;...Full Text Available

UK PubMed Central (United Kingdom)

A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for assessment of age-related structural changes (dentin and pulp) of human teeth in...Full Text Available

UK PubMed Central (United Kingdom)

The effects of thiol-specific reagents on the amplitude of the electro-olfactogram (E.O.G.) responses elicited from frog olfactory mucosa by pulses of odorant vapours was studied. The impermeant thiol-specific...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This paper reports on the results of experiments into efficient higher-order anti-Stokes Raman conversion of tunable short-pulse XeCl laser radiation. The maximum output energy of the pumping laser, in which the radiation of a frequency-doubled dye laser is amplified by two XeCl laser amplifiers, is 55 mJ with a pulse duration of 1 ns FWHM. Using hydrogen gas as a Raman medium, a series of anti-Stokes lines up to the 12th order (121.5 nm) is generated in the vacuum ultraviolet (VUV) region. 16 references.

International Nuclear Information System (INIS)

Superconducting magnetic and inertial energy pulsed power systems are being developed for future theta-pinch, Tokamak, and laser fusion applications. The short term requirements for these applications are discussed along with present day accomplishments. Areas requiring a research and development effort are examined in detail. Subjects discussed include stresses, energy loss factors, conductor metallurgy, cryogenic requirements, and electrical limitations of superconducting magnetic storage systems; costs, applications, and present technology of homopolar systems; and switching problems associated with both systems.

International Nuclear Information System (INIS)

The paper presents results of experimental research on the interaction of a pulsed plasma-ion stream with a tungsten (W) target. The pulsed hydrogen plasma was produced within the RPI-IBIS (Multi-Rod Plasma Injector) facility at IPJ in Swierk. Measurements were carried out by means of optical spectroscopy and corpuscular diagnostic techniques. For experiments with the W-target the operational conditions (so-called PID mode) were chosen when a clean hydrogen plasma stream was generated. Attention was paid to the identification of WI and WII spectral lines.

CERN Document Server

In situ optical absorption spectroscopy was used to study the generation of E' centres in amorphous SiO_2 occurring by photo-induced breaking of Si-H groups under 4.7eV pulsed laser radiation. The dependence from laser intensity of the defect generation rate is consistent with a two-photon mechanism for Si-H rupture, while the growth and the saturation of the defects are conditioned by their concurrent annealing due to reaction with mobile hydrogen arising from the same precursor. A rate equation is proposed to model the kinetics of the defects and tested on experimental data.

Energy Technology Data Exchange (ETDEWEB)

We are investigating a novel insulator concept which involves the use of alternating layers of conductors and insulators with periods less than 1 mm. These structures perform many times better (about 1.5 to 4 times higher breakdown electric field) than conventional insulators in long pulse, short pulse, and alternating polarity applications. We present our ongoing studies investigating the degradation of the breakdown electric field resulting from surface roughness, the effect of gas pressure, and the performance of the insulator structure under bi-polar stress. Further, we present our initial modeling studies.

Energy Technology Data Exchange (ETDEWEB)

The grain boundary crystallographic misorientations of magnetic-pulse-welded (MPW) aluminum alloy (AA) 6061-T6 in linear and tubular configurations were examined using the electron backscattered diffraction (EBSD) technique. A refined structure of heavily deformed grains with higher grain boundary angles was observed in linear welds. Significant spalling was observed away from the joints, in the interior of tubular welds. The results show the complex interaction of shock waves with the materials during this impact welding process.

British Library Electronic Table of Contents (United Kingdom)

Ascochyta blight causes significant yield loss in pulse crops worldwide. Integrated disease management is essential to take advantage of cultivars with partial resistance to this disease. The most effective practices, established by decades of research, use a combination of disease-free seed, destruction or avoidance of inoculum sources, manipulation of sowing dates, seed and foliar fungicides, and cultivars with improved resistance. An understanding of the pathosystems and the inter-relationship between host, pathogen and the environment is essential to be able to make correct decisions for disease control without compromising the agronomic or economic ideal. For individual pathosystems, some components of the integrated management principles may need to be given greater consideration tha...

Energy Technology Data Exchange (ETDEWEB)

Two hypotheses are in the centre of this investigation, on the one hand the question, whether microwaves as exogenous fields alone are able to stimulate human muscle cells above-threshold, and on the other hand, whether microwaves as conditioning to cathodical electrical pulses can modify the excitation threshold and form. No excitation through the application of microwaves alone can be introduced at any subject. The conditioning of above-threshold cathodical electrical pulses with UMTS-microwaves leads not to a transgression of the threshold or the electrical muscle response (EMG) depending on the amplitude, the duration or the dose rate. (orig.)

International Nuclear Information System (INIS)

Experiments are described on a plasma cathode with biased grids to prevent entry of ions into the electron extraction gap. The cathode has potential applications to the generation of high-current pulsed electron beams. Operation at 20 A/cm"2 is theoretically possible. The source combines the low average power consumption of a plasma cathode with many of the attractive features of thermionic cathodes, such as space-charge-limited extractor gap electron flow, fast turn-on, and no diode closure. Initial experiments are reported at the 2 A/cm"2 level for pulse lengths to 160 #mu#s.

International Nuclear Information System (INIS)

In the framework of the Low Emittance Gun (LEG) project, high gradient acceleration of a low emittance electron beam will be necessary. In order to achieve this acceleration, a -500 kV, 250 ns FWHM, pulse will be applied between two electrodes. Those electrodes should sustain the pulsed field without arcing, must not outgas and must not emit electrons. Ion back bombardment, and dark current will be damaging to the electron source as well as for the low emittance beam. Electrodes of commercially available OFE copper, aluminium, stainless steel (SS), titanium and molybdenum were tested, following different procedures including plasma glow discharge cleaning.

International Nuclear Information System (INIS)

Conduction-band electrons, formed by pulse radiolysis of Degussa P25 TiO_2 particles, have been monitored by time-resolved microwave conductivity and found to undergo equilibrium localization and eventual recombination at the particle surface. In the presence of isopropyl alcohol recombination is retarded due to surface hole scavenging. The particle bulk can then be pumped with mobile electrons, which survive for seconds.

Energy Technology Data Exchange (ETDEWEB)

The MTX explored the plasma heating effects of 140 GHz microwaves from both Gyrotrons and from the IMP FEL wiggler. The Gyrotron was long pulse length (0.5 seconds maximum) and the FEL produced short-pulse length, high-peak power, single and burst modes of 140 GHZ microwaves. Full-power operations of the IMP FEL wiggler were commenced in April of 1992 and continued into October of 1992. The Experimental Test Accelerator H (ETA-II) provided a 50-nanosecond, 6-MeV, 2--3 kAmp electron beam that was introduced co-linear into the IMP FEL with a 140 GHz Gyrotron master oscillator (MO). The FEL was able to amplify the MO signal from approximately 7 kW to peaks consistently in the range of 1--2 GW. This microwave pulse was transmitted into the MTX and allowed the exploration of the linear and non-linear effects of short pulse, intense power in the MTX plasma. Single pulses were used to ...

Energy Technology Data Exchange (ETDEWEB)

Activation dose rates have been computed for the Poloidal Divertor Experiment Tokamak at the Princeton Plasma Physics Laboratory. Dose rates were computed in one-dimensional (cylindrical) geometry using the ANISN S/sub n/ transport theory code and the DKR radioactivity code. The EPR (DLC37F) 121-group coupled neutron-gamma cross section library was used with ANISN. For DKR, the 46-group neutron library of DCDLIB was employed. Dose rates were calculated for 1 minute, 1 hour, 6 hours, 24 hours, 1 week, and 1 month following a single pulse yielding 10/sup 15/ neutrons and for 2 hypothetical pulsing sequences. First, it was assumed that 10 pulses were conducted each day (1 hour apart) for 5 days. Second, it was assumed that 100 pulses were conducted each day (6 minutes apart) for 5 days. It was found that /sup 56/Mn and /sup 64/Cu are the main contributors to the dose at short time periods after shutdown, ...

Energy Technology Data Exchange (ETDEWEB)

Previous in vitro studies have demonstrated that Ho:YLF laser is capable of inducing physical and chemical changes on dental surfaces treated for caries prevention. The temperature in the pulp chamber was in vitro evaluated to as a function of the power and frequency of the laser irradiation. The purpose of this work is to verify the occurrence of pulp inflammation after Ho:YLF laser irradiation using different parameters in rabbits' teeth. The premolars and molars of ten rabbits (NZB) were divided in two groups according to the irradiation energy values of a Ho:YLF laser prototype operating at 2.065{mu}m wave length, frequency of O,5Hz and pulse length of 250{mu}s. An group A teeth were irradiated with using ten pulses of 334mJ/pulse of a Ho:YLF laser prototype operating at O.5Hz, and group B, with 512mJ/pulse. Animals were killed by transcardiac perfusion and the samples were prepared for ...

Energy Technology Data Exchange (ETDEWEB)

In the two decades since the presentation of the first experimental results, the study of high-power microwaves (HPM) has aimed at the production of microwave pulses with ever higher peak power and ever larger energy content. Drawing on the electrical pulsed power and relativistic electron beam technologies, a mix of sources have produced power levels in excess of 1 GW and pulse energies of tens to a thousand joules in both the centimeter and millimeter wavelength ranges. The potential for military applications of such powerful bursts became a major driving force for substantial research programs -- and considerable advancements -- in the United States and the former Soviet Union. The end of the Cold War and a reexamination of national priorities has diminished the momentum of military HPM development in these countries. Nevertheless, the field hasn`t reached its limits, in capability or applicability, and one sees at ...

International Nuclear Information System (INIS)

We describe a new apparatus that combines pulsed laser excitation in a molecular beam with surface-science methods for preparation of clean single-crystal surfaces and detection of adsorbates to enable state-selected studies of gas-surface reaction dynamics. Reactant molecules are prepared in specific vibrationally excited states via overtone pumping using tunable, narrow-band laser radiation. The collision-free environment of the molecular beam prevents relaxation of the prepared molecules before impact on the target surface and enables complete control over the collision energy and incidence angle. Chemisorption products are detected after a given deposition time by Auger electron spectroscopy. To achieve sufficient beam flux of state-selected reactant molecules for product detection by standard surface-science techniques, we use a high-intensity, short-pulse molecular-beam source matched to the low duty cycle of the ...

DEFF Research Database (Denmark)

The blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signal response to neural stimulation is influenced by many factors that are unrelated to the stimulus. These factors are physiological, such as the resting venous cerebral blood volume (CBV(v)) and vessel size, as well as experimental, such as pulse sequence and static magnetic field strength (B(0)). Thus, it is difficult to compare task-induced fMRI signals across subjects, field strengths, and pulse sequences. This problem can be overcome by normalizing the neural activity-induced BOLD fMRI response by a global hypercapnia-induced BOLD signal. To demonstrate the effectiveness of the BOLD normalization approach, gradient-echo BOLD fMRI at 1.5, 4, and 7 T and spin-echo BOLD fMRI at 4 T were performed in human subjects. For neural stimulation, subjects performed sequential finger movements at 2 Hz, while for global stimulation, subjects breathed a 5% CO(2) ...

Energy Technology Data Exchange (ETDEWEB)

Propagation of an intense charged particle beam pulse through a background plasma is a common problem in astrophysics and plasma applications. The plasma can effectively neutralize the charge and current of the beam pulse, and thus provides a convenient medium for beam transport. The application of a small solenoidal magnetic field can drastically change the self-magnetic and self- electric fields of the beam pulse, thus allowing effective control of the beam transport through the background plasma. An analytic model is developed to describe the self-magnetic field of a finite- length ion beam pulse propagating in a cold background plasma in a solenoidal magnetic field. The analytic studies show that the solenoidal magnetic field starts to infuence the self-electric and self-magnetic fields when ?ce > ?pe?b, where ?ce = e?/mec is the electron gyrofrequency, ?pe is the electron plasma frequency, and ...

International Nuclear Information System (INIS)

The FEL electron linac consists of three buncher cavities: two accelerator cavities and a deflection cavity, each with its own phase-coherent rf source. All sources will be pulsed for 100 #mu#s at a 1-pps rate. The phase and amplitude stability requirements are +-1/2_0, and +-1/2%. There are two subharmonic bunchers, each requiring 5 kW at 108.33 MHz. All remaining cavities operate at 1300 MHz. The fundamental buncher requires 5 kW, whereas each of the accelerating cavities requires at least 3 MW. The deflection cavity requires up to 100 kW, which is coupled from one of the accelerator cavity rf sources. Prominent features of the rf system are the phase and amplitude control circuits and the multimegawatt klystron amplifiers. Three L3707 klystrons were obtained from the AMRAD radar site at White Sands, which was decommissioned in the early 1970s. The tubes originally were designed to produce 10-MW, 10-#mu#s pulses. Each tube has delivered over ...

Science.gov (United States)

The simulation of the temporal evolution of the various neutral gaseous species studied (O, O{sub 3}, H, OH, HO{sub 2}, H{sub 2}O{sub 2}, N, NO, NO{sub 2}, NO{sub 3}, N{sub 2}O, N{sub 2}O{sub 5}, HNO{sub 2}, and HNO{sub 3}) use corona effects. The physical conditions of the discharge were used. The reactions take place in dry or humid air, after the dissociation of O{sub 2}, N{sub 2}, and H{sub 2}O by an electronic pulse. When water vapor is present, there is a probability of production of H{sub 2}O{sub 2}, HNO{sub 2}, and HNO{sub 3} in air. Temperature and humidity have cumulative effects. With multiple pulses, the O{sub 3} maximal concentration is obtained for a limited number of pulses.

International Nuclear Information System (INIS)

This paper reports on the Burning Plasma Experiment (BPX) which when operating at a toroidal field of 8.1 tesla and a plasma current of 10.6 megamps, requires peak power of 1235 megawatts and total pulse energy of over 21 gigajoules. These requirements are twice and over four times the corresponding figures for the Tokamak Fusion Test Reactor (TFTR), respectively. The design of the BPX power system has evolved, along with the tokamak, over a period of several years and has included studies of several alternative approaches. The reapplication of the existing TFTR power and energy facilities has been basic to all approaches. Among the new sources of pulse power and energy that have been considered are: direct utility grid pulsing, new flywheel units, and lead-acid storage batteries. The toroidal field power requirements are the greatest of the BPX subsystems and, fortunately, are sufficiently free of dynamics to allow the ...

Energy Technology Data Exchange (ETDEWEB)

Thin films of the protein, lysozyme, have been deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. Frozen targets of 0.3-1.0 wt.% lysozyme dissolved in ultrapure water were irradiated by laser light at 355 nm with a fluence of 2 J/cm{sup 2}. The surface quality of the thin lysozyme films of different thickness deposited on 7 mm x 7 mm Si-<1 0 0>-wafers was investigated with scanning electron microscopy and atomic force microscopy. Already at comparatively low thickness, {approx}20 nm, the substrate is covered by intact lysozyme molecules and fragments. The concentration of lysozyme in the ice matrix apparently does not play any significant role for the morphology of the film. The morphology obtained with MAPLE has been compared with results for direct laser irradiation of a pressed lysozyme sample (i.e. pulsed laser deposition (PLD))

International Nuclear Information System (INIS)

CO poisoning is a major issue when reformate is used as a fuel in PEM fuel cells. Normally it is necessary to reduce the CO to very low levels (#approx#5 ppm) and CO tolerant catalysts, such as Pt-Ru, are often employed. As an alternative approach, we have studied the use of pulsed oxidation for the regeneration of CO poisoned cells. Results are presented for the regeneration of Pt and Pt-Ru anodes in a PEM fuel cell fed with CO concentrations as high as 10,000 ppm. The results show periodic removal of CO from the catalyst surface by pulsed oxidation can increase the average cell potential and increase overall efficiency. A method for enhancing the performance of a fuel cell stack using a microprocessor-based Fuel Cell Health Manager (FCHM) has been developed. The results of a cost/benefit analysis for the use of a FCHM on a 4 kW residential fuel cell system are presented. (author)

International Nuclear Information System (INIS)

Laser-induced change is studied of the optical absorption and luminescence due to F-H pairs generated by an electron pulse in SrF_2. It is found that laser irradiation near 2.34 eV at a delay of 26 #mu#s after an electron pulse by which F-H pairs are generated reduces the component I of the pairs that has a decay time of 59 #mu#s and optical absorption bands at 2.34 and 4.13 eV and enhances the component II that has a decay time of 7.7 ms and has optical absorption bands at 2.7 and 3.35 eV. Laser irradiation near 2.7 eV at a delay of 4 ms after the electron pulse is found to induce the reverse reaction. Studies of dichroism of the laser-induced reduction and enhancement of the optical absorption bands and the luminescence reveal that the direction of the #SIGMA#-#SIGMA# transition of the F_2"- molecular ion is converted by the transformation from I to II and vice versa. It is suggested that the component I corresponds to ...

CERN Document Server

We present measurements of the transmission of radio/microwave pulses through salt in the Cote Blanche salt mine operated by the North American Salt Company in St. Mary Parish, Louisiana. These results are from data taken in the southwestern region of the 1500 ft. (457 m) deep level of the mine on our third and most recent visit to the mine. We transmitted and received a fast, high-power, broadband pulse from within three vertical boreholes that were drilled to depths of 100 ft. (30 m) and 200 ft. below the 1500 ft. level using three different pairs of dipole antennas whose bandwidths span 125 to 900 MHz. By measuring the relative strength of the received pulses between boreholes with separations of 50 m and 169 m, we deduce the attenuation of the signal attributed to the salt medium. We fit the frequency dependence of the attenuation to a power law and find the best fit field attenuation lengths to be 93 \\pm 7 m at 150 ...

International Nuclear Information System (INIS)

The design and analysis of a high brightness electron beam experiment under construction at Sandia National Laboratory is presented. The beam energy is 12 MeV, the current 35 endash 40 kA, the rms radius 0.5 mm, and the pulse duration FWHM 40 ns. The accelerator is SABRE [J. Corley, J. A. Alexander, P. J. Pankuch, C. E. Heath, D. L. Johnson, J. J. Ramirez, and G. J. Denison, in Proceedings of the Eighth International IEEE Pulsed Power Conference, San Diego, California, 1991 (IEEE, New York, 1991), p. 920], a pulsed inductive voltage adder, and the electron source is a magnetically immersed foilless diode. This experiment has as its goal to stretch the technology to the edge and produce the highest possible electron current in a submillimiter radius beam. copyright 1996 American Institute of Physics.

Energy Technology Data Exchange (ETDEWEB)

The AP-0 Target Hall Collection Lens is a pulsed device which focuses anti-protons just downstream of the Target. Since the angles at which the anti-protons depart the Target can be quite large, a very high focusing strength is required to maximize anti-proton capture into the downstream Debuncher Ring. The current design of the Collection Lens was designed to operate with a focusing gradient of 1,000 T/m. However, multiple failures of early devices resulted in lowering the normal operating gradient to about 750 T/m. At this gradient, the Lens design fares much better, lasting several million pulses, but ultimately still fails. A Finite Element Analysis (FEA) has been performed on this Collection Lens design to help determine the cause and/or nature of the failures. The Collection Lens magnetic field is created by passing high current through a central conductor cylinder. A uniform current distribution through the cylinder will create a ...

International Nuclear Information System (INIS)

We have studied the efficiency of ozone production by pulsed positive corona discharge in coaxial wire-cylinder geometry at atmospheric pressure. A corona discharge was generated by short (#approx#150 ns) high voltage pulses applied between a silver coated copper wire anode and stainless steel cylinder cathode in synthetic air. A pyrex probe and Teflon tube was used for collecting discharge products and an ozone concentration was monitored outside of the discharge chamber by a non-dispersive UV absorption technique. The production of ozone was investigated as a function of energy density (10"-"4-3x10"-"1 Wh l"-"1) delivered to the discharge volume by combining the discharge frequency (0.1-10 Hz) and airflow rate (1-32 l min"-"1). From ozone concentration measurements we have evaluated the ozone production, yield and production energy cost. The ozone production yield and cost vary in the range of 15-55 g kWh"-"1 and 35-110 eV/molecule. (author)

Energy Technology Data Exchange (ETDEWEB)

Recently, a drive laser for an S-band (2.86 GHz) rf photoinjector, designed to provide a pulse that has a flat temporal and spatial profile, has been built, commissioned, and put into service as part of the LLNL Compton-scattering monoenergetic {gamma}-ray source program. This laser is based on an all-fiber oscillator and front-end amplification system, and provides both the laser light to generate the electrons as well as the rf signal that is amplified to accelerate them. Now, a new 11.424 GHz photoinjector is being developed, which has required a revised design for the laser system. The higher frequency has placed more stringent requirements on the synchronization stability, delivered pulse length, and pulse rise times to maintain the desired emittance. Presented here are the overall design and measured performance of the current system and a discussion of what changes are being made to address observed shortcomings and ...

Energy Technology Data Exchange (ETDEWEB)

Safety standards for exposure to radiofrequency radiation must be based upon biologic consequences of exposure to such environments. Behavioral-based measures are considered to be the most-sensitive indices of biological effects. Current safety guidelines are based upon average power density and may not be relevant to the high-peak-power, short pulse width microwave radiation produced by newly developed high peak power microwave sources. The effects of exposure to high-peak-power radiation on reflexive responding and motor function in Fischer 344/N rats were assessed by measuring startle and general activity, and disruption of on-going performance of a rotarod task, respectively. The emitter used was the TEMPO repeat pulse axially extracted vircator. Exposure to single pulses resulted in significant startle responses. Exposure to 1 pps for 10 s produced significant alterations in baseline activity and marked disruption of ...

Energy Technology Data Exchange (ETDEWEB)

A future e{sup -}-e{sup +} (electron-positron) linear collider can be configured with perhaps minimal modification to serve as an {gamma}-{gamma} (gamma-gamma) or a e{sup -}-{gamma} collider. This is accomplished by Compton-backscattering low energy photons (from a laser source) off of the high-energy electron beams prior to the crossing of the electron beams. However, to be competitive with the e{sup -}-e{sup +} configuration, the luminosity cannot be compromised in the process. This requires that the laser source deliver a sufficient number of photons per pulse with a pulse format and rate matching that of the electron beams. As it turns out, this requires an average optical power of 5-15 kW from the laser which is beyond the current state of the art. In this paper, we address how to generate the required pulse format and how the high average power requirement can be met with conventional laser technology. We also address ...

Energy Technology Data Exchange (ETDEWEB)

At Himeji Institute of Technology, the high power microwaves with the peak power of 20 MW, frequency of 12 GHz and pulse duration of 14 ns have been produced with a virtual cathode oscillator (vircator). These high power microwaves offer new applications in various fields. One problem in laser-triggered lightning experiment is the strong attenuation of laser energy by rain, cloud and laser-produced plasma. Microwaves propagate in thundercloud with small loss, and also are able to irradiate much extensive region of targets. In this paper, the fundamental experiment on the air breakdown induced by high power, short pulse microwaves is reported. The experimental setup of the vircator diode for microwave generation is shown. The typical evolution of diode voltage, electron beam current and microwave emission from the top in the course of time is shown. The experimental setup for microwave-induced air breakdown and the experimental procedure are ...

International Nuclear Information System (INIS)

An electric propulsion concept suitable for delivering heavy payloads from low earth orbit (LEO) to high energy earth orbit is proposed. The system consists of a number of pulsed inductive plasma thrusters powered by a 100 kWe space nuclear power system. The pulsed plasma thruster is a relatively simple electrodeless device. It also exhibits adequate conversion to thrust power in the desired I sub sp regime of 1500 to 3000 seconds for optimal payload transfer from low earth to high earth orbit. Because of these features and the fact that the nuclear power unit will be capable of delivering sustained high power levels throughout the duration of any given mission, the system presented appears to be a very promising propulsion candidate for advanced orbital transfer vehicle (OTV) applications. An OTV, which makes use of this propulsion system and which has been designed to lift a 9000-lb payload into geosynchronous earth orbit, (GEO) is also ...

Energy Technology Data Exchange (ETDEWEB)

A novel compact CT-guided intensity modulated proton radiotherapy (IMPT) system is described. The system is being designed to deliver fast IMPT so that larger target volumes and motion management can be accomplished. The system will be ideal for large and complex target volumes in young patients. The basis of the design is the dielectric wall accelerator (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL). The DWA uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system will produce individual pulses that can be varied in intensity, energy and spot width. The IMPT planning system will optimize delivery characteristics. The system will be capable of being sited in a ...

British Library Electronic Table of Contents (United Kingdom)

Wavy interface morphology is observed in Magnetic Pulse Welding (MPW) similarly to that of the Explosion Welding process (EXW). It is recognized that interfacial waves are formed in a periodic manner and have well defined wavelength and amplitude. The phenomenon of wave formation in EXW has been subjected to extensive investigations in which empirical and numerical models have been published. In the present study, a wave formation mechanism for MPW is presented. This wave-creation mechanism was studied by evaluating the influence of sample geometry on wave morphology using stereoscopic optical microscopy. It was found that interfacial waves are formed in a Kelvin-Helmholtz instability mechanism. Reflected shock waves interact with the welding collision point at the weld interface, where in...

International Nuclear Information System (INIS)

The intensity of erbium up-conversion luminescence could be limited by a saturation effect due to increased pump power. We studied the luminescence saturation of the 550 nm emission on erbium-doped, SiO_2-TiO_2 sol-gel powders under pulsed excitation at 979 and 1532 nm. From the latter, the up-converted luminescence intensity decreased with increasing excitation power, whereas no saturation was observed at 979 nm excitation. We proposed that the saturation effect is determined by the pump power, the erbium content and the lifetime of the corresponding first excited states at different pumping schemes.

International Nuclear Information System (INIS)

Knighton et al. used a pulsed high pressure mass spectrometer to examine thermal electron detachment from C_6F_6"-. This technique had been used earlier for the measurement or detachment rate coefficients for azulene anions as a function of temperature. C_6F_6"- and c-C_4F_6"- have been studied by Datskos et al. using a pulsed drift tube. In our laboratory, we have used a flowing afterglow Langmuir probe (FALP) apparatus to measure the thermal electron detachment rate coefficient for c-C_4F_8"- ions at 375 K. We have also measured the electron attachment rate coefficient for c-C_4F_8 at 303 K and 375 K. (author).

British Library Electronic Table of Contents (United Kingdom)

Summary The effects of high-intensity pulsed electromagnetic stimulation (HIPEMS) on proliferation and differentiation of neonatal rat neural stem cells in vitro were investigated. Neural stem cells derived from neonatal rats were exposed to 0.1 Hz, 0.5-10 Tesla (T) [8 groups of B-I, respectively], 5 stimuli of HIPEMF. The sham exposure controls were correspondingly established. Inverted phase contrast microscope was used to observe the cultured cells, MTT assay to detect the viability of the cells as expressed by absorbance (A) value, and flow cytometry to measure differentiation of neural stem cells. The results showed that A values of neural stem cells in both 3.0 T and 4.0 T groups were significantly higher than the other groups 24 to 168 h post HPEMS, indicating a strong promotion of ...

International Nuclear Information System (INIS)

Real-time neutron powder diffraction and small-angle scattering techniques have been developed on the TOF diffractometer DN-2 at the IBR-2 pulsed reactor at JINR (Dubna) with a total flux on the sample of 10"7 neutrons cm"-"2s"-"1 and a resolution of about 1%. A special arrangement of the detector system ensures a high counting rate of diffracted neutrons. Depending upon sample type and experimental conditions, the measuring time t_s of one neutron pattern varies from a few minutes to several seconds. The performance of the diffractometer is discussed and typical data are shown to demonstrate current achievements using real-time techniques at a pulsed reactor. (orig.).

International Nuclear Information System (INIS)

The opportunity of use self-maintained plasma-beam discharge in an extended pulsing plasma diode of low pressure for making powerful sources of the soft X-rays is investigated. Conditions of formation of the self-maintained plasma-beam discharge are determined. The mode of making of dense high-temperature plasma on the basis of stannum ions in the discharge is shown. The stannum ions are used as a working element of a radiation sources at pulsing power of electron beam P?10...100 MW. Results of the examination on formation of the dense (np?1016 cm3), small sizes (le?100 eV in conditions of working material evaporation from the anode are given. The total contribution of energy to the discharge has made W < 20 J.

Energy Technology Data Exchange (ETDEWEB)

In this work, the pulse plasma nitriding process of pure iron is modelled using a kinetic model derived from the Fick's laws. This approach based on the error function model allows to simulate the growth kinetics of a biphase configuration consisting of {gamma}'-Fe{sub 4}N{sub 1-x} and {epsilon}-Fe{sub 2-3}N iron nitrides under specified conditions. By coupling the kinetics data about the diffusivities of nitrogen in {alpha}-Fe, {gamma}' and {epsilon} phases to the thermodynamic description of the Fe-N phase diagram, it is possible to evaluate the kinetic constant at each growing phase interface, the thickness of nitrided layer, and predict the nitrogen concentration profiles. The comparison between the experimental and theoretical results shows the reliability of the simulation results.

International Nuclear Information System (INIS)

Radiation from an ultrastable 240 GHz solid state source has been injected, through an isolator, into the cavity of the University of California, Santa Barbara millimeter-wave free-electron laser (FEL). High-power FEL emission, normally distributed among many of the cavity's longitudinal modes, is concentrated into the single mode to which the solid state source has been tuned. The linewidth of the FEL emission is 0.5 MHz, consistent with the Fourier transform limit for the 2 #mu#s pulses. This demonstration of frequency-stable, ultranarrow-band FEL emission is a critical milestone on the road to FEL-based pulsed electron paramagnetic resonance spectroscopy.

International Nuclear Information System (INIS)

This paper is concerned with the real time automatic discriminating of flaws from two categories; i. cracks (planar defect) and ii. Non-cracks (volumetric defect such as cluster porosity and slag) using pulse-echo ultrasound. The raw ultrasonic flaws signal were collected from a computerized robotic plane scanning system over the whole of each reflector as the primary source of data. The signal is then filtered and the analysis in both time and frequency domain were executed to obtain the selected feature. The real time feature analysis techniques measured the number of peaks, maximum index, pulse duration, rise time and fall time. The obtained features could be used to distinguish between quantitatively classified flaws by using various tools in artificial intelligence such as neural networks. The proposed algorithm and complete system were implemented in a computer software developed using Microsoft Visual BASIC 6.0 (author)

International Nuclear Information System (INIS)

Formation of oxidizing and reducing radicals was studied by pulse radiolysis of [Fe(CN)_6]"4"- - BrO_3"- - CN"- system in ethylene glycol - water solvent mixture. Oxidizing #centre dot#BrO_2 and BrO radicals formed by electron scavenging with #centre dot#BrO_2"- were identified and their reactions were investigated. The reaction of hydroxyl radicals with ethylene glycol leads to formation of reactive radicals with reducing properties and of compounds which reduce slowly in dark the ferricyanide formed in the reaction of #centre dot#BrO_2 radical with ferrocyanide. (author) 21 refs.; 7 figs.

British Library Electronic Table of Contents (United Kingdom)

Resistive switching memory is a very promising technology for emerging nonvolatile memory applications. Generally, the switching behavior is triggered by a sweep or pulse voltage. In this paper, a charged capacitor is proposed to be used as the external electrical source to program a resistive switching element. From theoretical analyses based on a set behavior model, the capacitor approach can program the device efficiently. Compared with sweep or pulse mode, capacitor driving method can greatly reduce over-programming after the set event, and thus improve the resistance uniformity. The experimental results performed on Cu/ZrO2:Cu/Pt device support this conclusion quite well. The proposed methodology has great value for achieving a reliable resistive switching, which is important for high...

Energy Technology Data Exchange (ETDEWEB)

A three-light, three-lever discrete avoidance behavioral task was initiated to study the effects of a 500-675 rad neutron pulse upon performance. Eight primates performed the task for 4 h(3.5 h postexposure) on exposure day and for 4 h on each of 3 d postexposure. For the exposure day, five subjects had a decrease in correct responses, seven had increased reaction times, and six experienced productive emesis within 3.5 hours postexposure. Although the performance degradations were not severe, these data suggest that the performance of time critical tasks could be significantly impaired.

International Nuclear Information System (INIS)

We present the design, analysis, and results of the high brightness electron beam experiments currently under investigation at Sandia National Laboratories. The anticipated beam parameters are the following: energy 12 MeV, current 35 endash 40 kA, rms radius 0.5 mm, and pulse duration 40 ns full width at half-maximum. The accelerator is SABRE, a pulsed linear inductive voltage adder modified to higher impedance, and the electron source is a magnetically immersed foilless electron diode. 20 endash 30 T solenoidal magnets are required to insulate the diode and contain the beam to its extremely small-sized (1 mm) envelope. These experiments are designed to push the technology to produce the highest possible electron current in a submillimeter radius beam. Design, numerical simulations, and experimental results are presented. copyright 1997 American Institute of Physics.

Energy Technology Data Exchange (ETDEWEB)

One-electron oxidation of several derivatives of pyrazolin-5-one, including the drug antipyrine, were studied by pulse radiolysis of aqueous solutions. All the compounds were found to be oxidized by Br2 rapidly but considerably more slowly by weaker oxidants, such as peroxyl radicals. From redox equilibria using p-methoxyphenol and N,N,N',N'-tetramethyl-p-phenylenediamine as reference compounds, the one-electron oxidation potentials of the methyl-substituted 2-pyrazolin-5-ones were found to be in the range of 0.32-0.39 V versus normal hydrogen electrode. The relevance of these findings to the properties of the drug nafazatrom is discussed. Antipyrine was found to have a much higher oxidation potential, estimated as 1.2-1.5 V, which is rationalized on the basis of the phenyl substitution and lack of resonance stabilization of the radical cation.

Science.gov (United States)

In this paper we study theoretically a pulsed corona discharge plasma in air at atmospheric pressure. A self consistent one-dimensional model, using a flux-corrected transport numerical scheme, is presented to achieve it. The charged particle kinetics in this model are described by one-dimensional continuity equations coupled with Poisson's equations. The spatio-temporal local field, charge density variations and the velocity profile of an ionizing front are calculated to describe the dynamical behavior of corona discharge plasmas. The simulation results of a wire-in-cylinder corona discharge plasma explain the physical mechanisms of discharge processes. These results may also be apply to obtain the optimizing parameters for designing the plasma reactor.

Energy Technology Data Exchange (ETDEWEB)

The effects of spin diffusion on the free induction decay (FID) of protons associated with the noncrystalline domains of two polymers, polyethylene and blended Nylon 66 (ZYTEL-408), have been examined using Goldman--Shen NMR pulse sequence ((1/2)..pi..x-t/sub 0/-(1/2)..pi..x-bar-tau-(1/2)..pi..x-t). At tau< or approx. =100 ..mu..s, the FID is drastically distorted from the exponential form while at longer tau(tau> or approx. =500 ..mu..s) an exponential FID is observed; but its transverse spin relaxation rate is smaller than that of the FID obtained after a single (1/2)..pi..x pulse and approaches this value at the limit of large tau. These findings are interpreted in terms of the theory of rapid spin diffusion. The spatial variation in the spin relaxation rate within the noncrystalline domain is inferred.

Energy Technology Data Exchange (ETDEWEB)

Magnetic pulse welding, a cold solid state bonding process, is becoming a viable replacement for conventional fusion welding processes and explosive welding. The process is presented here along with its fundamental equations and applications of similar and dissimilar welds are illustrated along with typical interface microstructures. (orig.) [German] Magnetimpuls-schweissen, ein Verbindungsverfahren im kalten Festzustand, wird ein funktionsfaehiger Ersatz fuer das herkoemmliche Schmelzschweissverfahren und das Explosionsschweissverfahren. Das Verfahren wird hier mit seinen grundlegenden Gleichungen vorgestellt, und Anwendungen von aehnlichen und unaehnlichen Schweissungen werden mit typischen Schnittstellen-Mikrostrukturen veranschaulicht. (orig.)

CERN Document Server

An effect of laser-cooling of water was observed for the first time with a temperature decrease dT = -2.2 K after irradiation of liquid water surface by a powerful Ar-Xe pulse laser with a pulse energy of about 1 J and wavelength L = 1.73, 2.63 and 2.65 um. The discovered effect can apparently be ascribed to the optical excitation of vibrational states of H2O molecules followed by an endothermic consolidation of chemically active excited molecules into a quasi-stable cluster-like structure. The measured time dependences of the cooling effect show that a typical life time of the new state of water amounts to hours. It has also been shown that the life time of the excited vibrational molecular states due to a radiation trapping effect can be estimated to at least hundreds of seconds.

Energy Technology Data Exchange (ETDEWEB)

A new technique for ion implantation into concave surface of insulating materials is proposed and experimentally studied. The principle is roughly described by referring to modifying inner surface of a PET (polyethylene terephthalate) bottle. An electrode that is supplied with positive high-voltage pulses is inserted into the bottle. Both plasma formation and ion implantation are simultaneously realized by the same high-voltage pulses. Ion sheath with a certain thickness that depends on plasma parameters is formed just on the inner surface of the bottle. Since the plasma potential is very close to that of the electrode, ions from the plasma are accelerated in the sheath and implanted perpendicularly into the bottle's inner surface. Laser Raman spectroscopy shows that the inner surface of an ion-implanted PET bottle is modified into DLC (diamond-like carbon). Gas permeation measurement shows that gas-barrier property enhances due to the ...

British Library Electronic Table of Contents (United Kingdom)

Magnetic pulse welding is a solid state impact welding process, similar to explosive welding, which produces metallurgical bond by oblique high-speed impact between two metal bodies. This violent impact removes the metal surface oxide layers and then joins the two atomic level clean metal surfaces together by the incidental compression pressure. The impact velocity is at 200?400?m/s and the being welded metal surface undergoes severe plastic deformation with strain rate in the order of 106?107?s?1. The ultrafine-grained structure was observed on the welded interface. This article studied two types of similar material lap joint interfaces and the base metals were aluminum alloy 6061 and copper alloy 110. Nano-indentation testing shows that the welded interfaces have significantly greater ha...

British Library Electronic Table of Contents (United Kingdom)

Abstract Background and Purpose: During laser lithotripsy, working instruments are often in close proximity to the distal fiber tip and may be damaged accidentally or even intentionally. The aim of this study was to compare the amount of damage to a standard guidewire and the nitinol wires of endourologic retrieval baskets that were affected by three different clinically available laser systems. Materials and Methods: The impact of pulsed laser irradiation on a standard hydrophilic guidewire and a retrieval basket were investigated. One infrared (IR) laser system (holmium:yttrium-aluminum-garnet [Ho:YAG]: ????=???2100???nm) and two laser systems emitting light in the visible (VIS) spectral range (frequency-doubled double-pulse neodymium:YAG [FREDDY]: ????=???532???nm/1064???nm and flashl...

Energy Technology Data Exchange (ETDEWEB)

It is shown that a gun similar to that in the SSPX could demonstrate the high fields required for Pulsed Spheromak reactors merely by prolonging the pulse. Important considerations are choosing the voltage to exceed ohmic losses; designing the gun to avoid wasteful short-circuiting of current within the gun; and the injection efficiency factor, f, determined by the ''sag'' in the profile of {lambda} = {mu}{sub o}j/B. Typically f = 0.75 in experiments, giving an overall efficiency > 50 % if short-circuiting is avoided. Theoretical transport models agree qualitatively with the need for a finite gradient in h to pump in helicity by current-driven tearing modes and suggest that pressure-driven resistive modes would not compete with current-driven modes during a buildup to ohmic ignition.

British Library Electronic Table of Contents (United Kingdom)

This paper investigates the effects of the electric current pulse (ECP) on the interface stability of Al-4.5% Cu alloy during the directional solidification. Experimental results show both the cellular spacing and the mushy zone depth decrease with increasing current density, moreover, the solid-liquid interface morphology transforms from dendritic to cellular or even planar interface. The secondary dendrites are suppressed due to the homogeneous distribution of the solute and the increase of temperature gradient originated from ECP. The decrease of the cellular spacing results from branching of the cellular tip caused by Joule heat of the current exerting on cellular tip.

International Nuclear Information System (INIS)

We present and characterize a very efficient optical device that employs the plasma mirror technique to increase the contrast of high-power laser systems. Contrast improvements higher than 104 with 50% transmission are shown to be routinely achieved on a typical 10 TW laser system when the pulse is reflected on two consecutive plasma mirrors. Used at the end of the laser system, this double plasma mirror preserves the spatial profile of the initial beam, is unaffected by shot-to-shot fluctuations, and is suitable for most high peak power laser systems. We use the generation of high-order harmonics as an effective test for the contrast improvement produced by the double plasma mirrors. (authors)

CERN Document Server

A new methane cold neutron source has been tested at the IBR-2 pulsed reactor at the Frank Laboratory of Neutron Physics. In a paper the results of experiments at neutron diffractometers HRFD and DN-2 which are placed at the IBR-2 from the methane moderator side are given. A comparison with the results obtained with the conventional water comb-like moderator is performed. The perspectives of the cold source for various kinds of neutron diffraction experiments, including atomic and magnetic structural analysis and real time experiments are discussed. It is shown, that for a huge number of the experiments which are performing at both HRFD and DN-2 the methane cold neutron source provides the better conditions than water comb-like moderator.

International Nuclear Information System (INIS)

A comparison is made of the response of a count ratemeter and a pulse counter using the mathematical tool of the Z transform. Transform Z is used for the solution of the convolution integral interpreting the analog output of the count ratemeter used for recording characteristic radiation, excited in the moving beam. The comparison of count rates obtained by the count ratemeter during continuous analysis and the pulse counter during discontinuous measurement gave the transfer function of the count ratemeter in the actual range of count rate. Also discussed is the use of the transfer function for localizing concentration changes in the sample. The use of the described method is demonstrated on the determination of the tin content in tungsten using continuous radionuclide X-ray fluorescence analysis. (B.S.).

Energy Technology Data Exchange (ETDEWEB)

The study examines advances in Chinese High Power Microwaves (HPM) research and its associated technologies: pulsed power, high-power microwave sources, and high-power microwave components. It draws from open literature published in Chinese and English, communication with US scholars who have visited China recently, and communication with Chinese researchers in the United States. The study is limited to frequencies ranging from 1 GHz to 300 GHz. It includes both high peak power microwaves and high average power microwaves. The technical review section of this study is ordered in technological sequence, starting with the pulsed-power systems required to form the intense relativistic electron beams, then assessing microwave source research and development, and finally discussing high-power microwave components.

International Nuclear Information System (INIS)

We propose a method of plasma production by capacity-coupled multidischarge (CCMD) at atmospheric pressure. The discharge gaps in the CCMD consist of a common electrode and a number of compact electrodes (CCE) which are directly coupled with small capacitors for quenching the discharge. A simple CCE structure is provided by a cylindrical capacitor, the inner conductor of which is used as a gap electrode. A short pulse discharge is observed to appear homogeneously at each CCE. A charge transfer for the single-pulsed discharge is 10-100 times as large as that of the conventional dielectric barrier discharge. A high efficiency of ozone production has been confirmed in the CCMD using O_2 gas. A device configuration of the CCMD is quite flexible with respect to its geometrical shape and size. The CCMD could be used to produce plasmas for various kinds of industrial applications at atmospheric pressure.

Energy Technology Data Exchange (ETDEWEB)

Plasma nitriding is usually used for ferrous materials to improve their surface properties. Knowledge of the properties of thin surface layers is essential for designing engineering components with optimal wear performance. In our study, we investigated the microstructural, mechanical and tribological properties of plasma- and pulse plasma-nitrided AISI 4140 steel in comparison to hardened steel. The influence of nitriding case depth as well as the presence of a compound layer on its tribological behaviour was also examined. Plasma and pulse plasma nitriding were carried out using commercial nitriding processes. Nitrided samples were fully characterised, using metallographic, SEM microscopic, microhardness and profilometric techniques, before and after wear testing. Wear tests were performed on a pin-on-disc wear testing machine in which nitrided pins were mated to hardened ball bearing steel discs. The wear tests were carried out under dry ...

Energy Technology Data Exchange (ETDEWEB)

The state of lithium electrode surface after contact with triethylamine-modified propylene carbonate solutions of lithium perchlorate was studied using the pulse galvanostatic technique as well as methods of SIMS and electron microscopy. It was shown that amine added into the solutions stabilizes the state of lithium and prevents the formation of a secondary porous passive film on the lithium surface. Chemical composition of the primary film remains unchanged. Certain properties of passive films formed in electrolyte solutions studied were evaluated.

Energy Technology Data Exchange (ETDEWEB)

A review of theoretical and observational research on the magnetopause during 1987-1990. Starting with recent work on magnetic reconnection, the review proceeds to magnetopause surface wave phenomena, including the controversy over the role of solar wind pressure pulses in the coupling process and in the mimicking of flux transfer events signatures, and finishes with the magnetopause structure and associated wave phenomena. Recent advances in computer modeling of the magnetopause and the pertinent processes are also discussed. 108 refs.

International Nuclear Information System (INIS)

The high pressure discharges (pulsed or D C corona, barrier, gliding and the others), have been studied both experimentally and theoretically as sources of low temperature plasma for pollution control technologies. The potential of electrical discharge methods has been demonstrated for the decomposition of many types of VOC. The air or oxygen are used as a feed gas in which pollutant is diluted. The ozone production in air or oxygen in such discharges is also discussed

International Nuclear Information System (INIS)

The salient features of the near-infrared free-electron laser (FEL) that is under construction at the new Darmstadt superconducting 130-MeV electron accelerator are discussed. Special attention is given to the layout and the parameters of the accelerator, the layout of the planned FEL experiment, the characteristics of the electron gun, the subharmonic chopper-buncher system, and the hybrid undulator system of the Darmstadt FEL. A comparison of the planned Darmstadt FEL with conventional lasers, with respect to the pulse and wavelength region, is presented. 15 refs.

International Nuclear Information System (INIS)

Possibility for using a sodium iodide scintillator as a reference signal source is considered. Experimental data on studying the performance of a gamma thickness gage with an additional scintillator are given. Results of experimental investigations of a thickness gage dummy proved practical expediency of the principle being considered. It is established, in particular, that the device is ready to operate without warm-up with a constant sensitivity, the deviation not exceeding 0.5%, in the ambient temperature range of 15-25 deg C.

Energy Technology Data Exchange (ETDEWEB)

The peculiarities of pulsed laser melting and evaporation of the superconducting ceramics are analyzed by means of numerical simulation. The appearance of the overheated metastable states in solid and liquid phases is shown as a result of the phase front dynamics and volume nature of laser energy release. A method of dynamic adaptation for the multifront Stefan problem is proposed.

Energy Technology Data Exchange (ETDEWEB)

An optical voltage reference for providing an alternative to a battery source. The optical reference apparatus provides a temperature stable, high precision, isolated voltage reference through the use of optical isolation techniques to eliminate current and impedance coupling errors. Pulse rate frequency modulation is employed to eliminate errors in the optical transmission link while phase-lock feedback is employed to stabilize the frequency to voltage transfer function.

CERN Document Server

Using spectral hole-burning-based ultraslow group velocity in a dilute solid medium, we report enhanced photon echo efficiency three orders of magnitude higher than that in a nonslow light regime. The enhancement is due to exponentially increased absorption of an optical data pulse owing to the enhanced photon-atom interaction in an ultraslow light regime, whereas echo reabsorption is negligibly small due to group-velocity dependent population depletion.

Wastenet

... Electro-Osmotic Pulse (EOP) technology forces moisture to flow through concrete surfaces against the hydraulic gradient when an electric field is applied to an embedded anode system. This flow is initiated by the movement of cations (positively charged ions) present in a porous medium such as concrete toward the negative earth. Water surrounding the cations moves with them. The Corps of Engineers owns and maintains many buried ...

Energy Technology Data Exchange (ETDEWEB)

Goal was developing optical methods for study of dynamic processes at the electrode/electrolyte interface. In the past year, optical second harmonic generation was used for time-resolved measurements of thallium deposition on Cu(111). The studies of carrier dynamics in photo-excited materials have involved both steady-state and picosecond time-resolved luminescence measurements following photoexcitation of the semiconductor material.

UK PubMed Central (United Kingdom)

A pulsed field gradient spin echo sequence has been incorporated in a nuclear magnetic resonance (NMR) imaging experiment to provide an image contrast dependent on local molecular self-diffusion. The...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A number of interactions between magnetic fields and matter is reviewed. The resulting forces range in magnitude from the very large, obtained in high-energy fields, to the weak ones caused by the magnetostriction of ferromagnets. The fundamentals of these interactions are highlighted, and the examples discussed are forces on dipoles, particle alignment, magnetostrictive forces, magnetic forming, magnetic stirring, levitation melting, and magnetic pulsing of tool steels. (orig.)

Energy Technology Data Exchange (ETDEWEB)

We use the method of Padg approximants and Fourier transform techniques to treat analytically the problem of transverse and longitudinal mode evolution in FELs. We obtain simple relations providing a transparent understanding of the dynamic of pulse propagation effects and of transverse mode guiding. We discuss the interplay with inhomogeneous broadening effects and derive gain formulae including longitudinal and transverse mode couplings.

Energy Technology Data Exchange (ETDEWEB)

A discussion is presented of the 750-KeV chopper experience with both proton and negative ion beams and the ability of these systems to tailor the Linac beam to the diverse requirements of its users; normal accelerator injection, neutron therapy beam, and electron cooling experiments. This flexibility plus a cleaner beam pulse, improved thyratron operation, and mechanical modularity are the results of recent improvements. Additional benefits have been increased reliability and ease of service to the 750-KeV chopper. 3 refs.

Energy Technology Data Exchange (ETDEWEB)

The properties of Mn-doped GaAs layers grown by laser deposition were investigated with measurements of Hall effect and magneto-optical Kerr effect (MOKE). The electrical and magnetic parameters of the layers were defined by growth temperature and quantity of sputtered Mn. It was shown that room-temperature ferromagnetism is revealed by MOKE and, after ruby laser 25 ns pulse annealing, by Hall effect measurements.

International Nuclear Information System (INIS)

Electron beams as a source of directed energy are under study at the Lawrence Livermore National Laboratory (LLNL). An intense 10-kA, 50-MeV, 50-ns full-width half-maximum, pulsed electron beam is generated by the prototype Advanced Test Accelerator (ATA) at the Laboratory's Site 300. Whenever the electron beam is stopped in materials, intense radiation is generated. Estimates based on available data in the literature show that for materials such as lead, photon radiation (x ray, gamma, bremsstrahlung) levels can be as large as 10"4 roentgens per pulse at 1 m in the zero-degree direction (i.e., the electron-beam direction). Neutrons, which are emitted isotropically, are produced at a level of 10"1"3 n/m"2 per pulse. Depending upon the number of pulses and the shielding geometry, the accumulated dose is potentially lethal to personnel and potentially damaging to instrumentation that may be used for ...

Energy Technology Data Exchange (ETDEWEB)

In this first quarterly technical report for DOE Contract No. DE-AC22-87PC79654, a description of the background, technology, and application is provided. The design and fabrication of advanced combustion chambers were completed during this period. Initial testing on both the bare metal and refractory lined advanced chambers were initiated. The units were tested initially with gas but primarily with coal. A Pittsburgh No. 8 pulverized coal was used for these test activities. Both advanced chambers pulsed well.

Energy Technology Data Exchange (ETDEWEB)

The results of the creep performance studies at temperatures from 700-1000 C with welds of alloy 800 HT, the manual shielded metal arc welds made with Githerm 85 and Grini 209 filler metals, as well as the MIG pulsed arc welds made with the Nicrofer S 206 and Nicrofer S 5520 filler metals, proved to be in very good agreement with the calculated characteristic values published on VdTUeV sheet 434 in comparative assessments based on creep values valid for a service period of 10 000 hours. The MIG pulsed arc weld made with the Nicrofer S 5520 filler metal achieved by far the best results and strength values comparable to those of the base material, whereas the values of the other welds were corresponding to calculated strength values of the base material reduced by 20%. (orig./CB) [Deutsch] Die im Temperaturbereich von 700-1000 C an Alloy 800 HT und den Elektrodenhandschweissverbindungen mit den Schweisszusaetzen Gritherm 85 und Grini 209, sowie ...

Energy Technology Data Exchange (ETDEWEB)

The most serious challenges in the design of chambers for inertial fusion energy (IFE) are 1) protecting the first wall from fusion energy pulses on the order of several hundred megajoules released in the form of x rays, target debris, and high energy neutrons, and 2) operating the chamber at a pulse repetition rate of 5-10 Hz (i.e., re-establishing, the wall protection and chamber conditions needed for beam propagation to the target between pulses). In meeting these challenges, designers have capitalized on the ability to separate the fusion burn physics from the geometry and environment of the fusion chamber. Most recent conceptual designs use gases or flowing liquids inside the chamber. Thin liquid layers of molten salt or metal and low pressure, high-Z gases can protect the first wall from x rays and target debris, while thick liquid layers have the added benefit of protecting structures from fusion neutrons thereby ...

UK PubMed Central (United Kingdom)

Salmonella enterica subsp. enterica serovar Typhimurium was isolated from diarrheic piglets in 2 periods, 2000–2001 (n = 25) and 2005–2006...Full Text Available

International Nuclear Information System (INIS)

A next generation e"+-e"- linear collider in the TeV range can be converted into a #gamma#-#gamma# collider by converting it to e"--e"- operation and then generating #gamma#-rays via Compton backscattering with optical beams. This provides unique access to some areas of fundamental physics as well as highly desirable redundancy to the collisions. The required optical beam (with a wavelength of about 1 micron) must have very high peak power, (about 1 TW) as well as average power (about 10 kW). To achieve a 1 : 1 conversion from an electron to #gamma#-quantum, each micropulse must contain about one Joule and must be about one picosecond long, the micropulse peak power being about one Terawatt. To match the electron beam pulse structure, a macropulse consists of a sequence of about one hundred micropulses separated by about one nanosecond, and the macropulses am repeated at a rate of about 100 Hz. Thus, the time average power is about 10 kW propose and analyze a ...

Energy Technology Data Exchange (ETDEWEB)

A multi-group neutron-gamma cross-section library in DTF-IV format is supplemented with electron production matrix to generate a coupled neutron-gamma-electron library. This is realized by estimating the contributions from Compton scattering, pair production and photoelectric effect to the electron production cross-sections. A novel application of this new library, which involves transport of neutrons, gammas and electrons, for estimating the Compton current due to a pulse of radiation in air is discussed.

Energy Technology Data Exchange (ETDEWEB)

The authors present design methodology and initial experimental results for a high power microwave switch. The switch is designed for application to the pulse compression system associated with the Next Linear Collider Test Accelerator (NLCTA). The switch is based on the excitation of a plasma layer within a silicon wafer by either a laser or an electron beam. They investigate problems associated with high power operation of such a switch. They explore solutions to the problems of thermal runaway, avalanche breakdown, photo-emission, and secondary emission.

Energy Technology Data Exchange (ETDEWEB)

Recently, the public has become aware of keywords like ''Quantum computer'' or ''Quantum cryptography''. Regarding their potential application in solid state based quantum information processing and their overall benefit in fundamental research quantum dots have gained more and more public interest. In this context, quantum dots are often referred to as ''artificial atoms'', a term subsuming their physical properties quite nicely and emphasizing the huge potential for further investigations. The basic mechanism to be considered is the theoretical model of a two-level system. A quantum dot itself represents this kind of system quite nicely, provided that only the presence or absence of a single exciton in the ground state of that structure is regarded. This concept can also be expanded to the presence of two excitons (bi-exciton). Transitions between the relevant levels can be ...

CERN Document Server

We present evidence for the existence of two ~35 day clocks in the Her X-1/HZ Her binary system. ~35 day modulations are observed 1) in the Turn-On cycles with two on- and two off-states, and 2) in the changing shape of the pulse profiles which re-appears regularly. The two ways of counting the 35 day cycles are generally in synchronization. This synchronization did apparently break down temporarily during the long Anomalous Low (AL3) which Her X-1 experienced in 1999/2000, in the sense that there must have been one extra Turn-On cycle. Our working hypothesis is that there are two clocks in the system, both with a period of about ~35 days: precession of the accretion disk (the less stable "Turn-On clock") and free precession of the neutron star (the more stable "Pulse profile clock"). We suggest that free precession of the neutron star is the master clock, and that the precession of the accretion disk is basically synchronized to that of the ...

CERN Document Server

We explore a planar GaAs/AlAs photonic microcavity using pump-probe spectroscopy. Free carriers are excited in the GaAs with short pump pulses. The time-resolved reflectivity is spectrally resolved short probe pulses. We show experimentally that the cavity resonance and its width depend on the dynamic refractive index of both the lambda-slab and the lambda/4 GaAs mirrors. We clearly observe a double exponential relaxation of both the the cavity resonance and its width, which is due to the different recombination timescales in the lambda-slab and the mirrors. In particular, the relaxation time due to the GaAs mirrors approaches the photon storage time of the cavity, a regime for which nonlinear effects have been predicted. The strongly non-single exponential behavior of the resonance and the width is in excellent agreement to a transfer-matrix model taking into account two recombination times. The change in width leads to a change in ...

CERN Document Server

We study the spectral and temporal behavior of the High Mass X-ray Binary A 0535+26 during a `pre-outburst flare' which took place ~5 d before the peak of a normal (type I) outburst in August/September 2005. We compare the studied behavior with that observed during the outburst. We analyse RXTE observations that monitored A 0535+26 during the outburst. We complete spectral and timing analyses of the data. We study the evolution of the pulse period, present energy-dependent pulse profiles both at the initial pre-outburst flare and close to outburst maximum, and measure how the cyclotron resonance-scattering feature (hereafter CRSF) evolves. We present three main results: a constant period P=103.3960(5)s is measured until periastron passage, followed by a spin-up with a decreasing period derivative of Pdot=(-1.69+/-0.04)x10^(-8)s/s at MJD 53618, and P remains constant again at the end of the main outburst. The spin-up provides evidence for the ...

Energy Technology Data Exchange (ETDEWEB)

This work was initiated to examine the effect of frequency and treatment temperature on the formation of nitrided layers and surface characteristics during plasma nitriding. Plasma nitriding experiments were performed with 316L austenitic stainless steel at the temperatures 400 .deg. C and 500 deg. C using a pulsed d.c. plasma with various frequencies in an atmosphere of N{sub 2}-H{sub 2} gas mixture. The microstructure and thickness of the nitrided layer and morphology of the nitrided surface were investigated using OM, SEM, XRD, EDS and AFM. XRD patterns revealed that the surface layer formed at 400 deg. C consisted of S phase only and CrN+Fe{sub 4}N nitrides at 500 .deg. C and no change of phase composition with frequency was observed. The compound layer thickened slightly with increased frequency. Also, the surface roughness increased as the frequency of the pulsed plasma increased from 50 to 5,000Hz.

Energy Technology Data Exchange (ETDEWEB)

This work presents the development of a streak camera 'jitter free' sweep unit synchronized on a femtosecond laser. This application of high voltage photoconductive switches ('High voltage Auston switch') yields subpicosecond resolution for accumulated images on streak camera on a few hundreds micro joule femtosecond laser. Two others applications of these photoconductive switches are studied: - ultrafast optical commutation by a Pockels cell directly driven by a photoconductive switch (rising edge < 100 ps and jitter < 2 ps), - laser pulse energy self-stabilization experimentally proving that driving a Pockels cell by a photoconductive switch can increase the stability of the laser pulse energy from 7 % to 0.7 % rms. Additionally, the application of the acoustic-optical programmable dispersive filter (Dazzler) to the self referenced spectral phase measurement is presented. As these measurements ...