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Measurement of Electrical Quantities in Pulse Power Systems

Description: Abstract: The Workshop on Measurement of Electrical Quantities in Pulse Power Systems addressed measurements in pulse systems having the characteristics of pulse duration less than a millisecond, system voltages greater than 10 kilovolts, and system currents greater than 10 kiloamperes. The presented papers were divided into four categories: voltage measurements; current measurements; power and energy measurements, and data acquisition. Included are discussions of applications of conventional measurement techniques and state-of-the-art systems.
Date: June 1982
Creator: McKnight, R. H. & Hebner, R. E., Jr.
Partner: UNT Libraries Government Documents Department

Stress Pulse-Trains from Multiple Reflection at a Zone of Many Discontinuities: a Notation for Machine Solution

Description: Abstract: "Presented in this report is a numerical method by which may be calculated the amplitudes of the trains of pulses that result when a single simple stress pulse encounters a zone of many abrupt discontinuities in a slender rod. The notational scheme employed enables the system of multitudes of individual progagating waves to be studied in terms of analogous number sets which may be mechanically generated. The notational concept and related operational rules, described in this report, have been used to program the problem for solution with the IBM 704 computer. The program is briefly discussed. Illustrative examples were computed for rods of two to ten discontinuities. These were compared with a pulse reflected in a rod of an unlimited number of steps."
Date: August 1962
Creator: Reed, R. P.
Partner: UNT Libraries Government Documents Department

Adaptive control of femtosecond pulse propagation in optical fibers

Description: We present an adaptive control loop that synthesizes fs-pulses that are self-correcting for higher order nonlinear effects when launched in a conventional single-mode fiber, nearly preserving the initial (t{approx}200 fs) pulse duration.
Date: January 1, 2001
Creator: Omenetto, F. G. (Fiorenzo G.); Taylor, Antoinette J.,; Moores, M. D. (Mark D.) & Reitze, David H.
Partner: UNT Libraries Government Documents Department

Analysis of output surface damage resulting from single 351 nm, 3 ns pulses on sub-nanosecond laser conditioned KD2PO4 crystals

Description: We observe that by conditioning DKDP using 500 ps laser pulses, the bulk damage threshold becomes essentially equivalent to the surface damage threshold. We report here the findings of our study of laser initiated output surface damage on 500 ps laser conditioned DKDP for test pulses at 351 nm, 3 ns. The relation between surface damage density and damaging fluence (r(f)) is presented for the first time and the morphologies of the surface sites are discussed. The results of this study suggest a surface conditioning effect resulting from exposure to 500 ps laser pulses.
Date: October 31, 2007
Creator: Jarboe, J; Adams, J J & Hackel, R
Partner: UNT Libraries Government Documents Department

The Use of Thyristors for Repetitive Narrow Pulse, High Power Switching

Description: Inverter type thyristors were switched repetitively to failure with 1 {micro}s pulses at repetition rates of 10, 50 and 100 pps and at peak currents up to 12 kA. Millions of pulses could be obtained before failure if the peak current were held at around 6 kA.
Date: January 13, 2000
Creator: BAYNE,S.B.; PORTNOY,W.M. & ROHWEIN,G.J.
Partner: UNT Libraries Government Documents Department

High average power, high current pulsed accelerator technology

Description: Which current pulsed accelerator technology was developed during the late 60`s through the late 80`s to satisfy the needs of various military related applications such as effects simulators, particle beam devices, free electron lasers, and as drivers for Inertial Confinement Fusion devices. The emphasis in these devices is to achieve very high peak power levels, with pulse lengths on the order of a few 10`s of nanoseconds, peak currents of up to 10`s of MA, and accelerating potentials of up to 10`s of MV. New which average power systems, incorporating thermal management techniques, are enabling the potential use of high peak power technology in a number of diverse industrial application areas such as materials processing, food processing, stack gas cleanup, and the destruction of organic contaminants. These systems employ semiconductor and saturable magnetic switches to achieve short pulse durations that can then be added to efficiently give MV accelerating, potentials while delivering average power levels of a few 100`s of kilowatts to perhaps many megawatts. The Repetitive High Energy Puled Power project is developing short-pulse, high current accelerator technology capable of generating beams with kJ`s of energy per pulse delivered to areas of 1000 cm{sup 2} or more using ions, electrons, or x-rays. Modular technology is employed to meet the needs of a variety of applications requiring from 100`s of kV to MV`s and from 10`s to 100`s of kA. Modest repetition rates, up to a few 100`s of pulses per second (PPS), allow these machines to deliver average currents on the order of a few 100`s of mA. The design and operation of the second generation 300 kW RHEPP-II machine, now being brought on-line to operate at 2.5 MV, 25 kA, and 100 PPS will be described in detail as one example of the new high average power, high ...
Date: May 1, 1995
Creator: Neau, E.L.
Partner: UNT Libraries Government Documents Department

Laser hazard analysis for various candidate diode lasers associated with the high resolution pulsed scanner.

Description: A laser hazard analysis and safety assessment was performed for each various laser diode candidates associated with the High Resolution Pulse Scanner based on the ANSI Standard Z136.1-2000, American National Standard for the Safe Use of Lasers. A theoretical laser hazard analysis model for this system was derived and an Excel{reg_sign} spreadsheet model was developed to answer the 'what if questions' associated with the various modes of operations for the various candidate diode lasers.
Date: October 1, 2004
Creator: Augustoni, Arnold L.
Partner: UNT Libraries Government Documents Department

SAR ambiguous range suppression.

Description: Pulsed Radar systems suffer range ambiguities, that is, echoes from pulses transmitted at different times arrive at the receiver simultaneously. Conventional mitigation techniques are not always adequate. However, pulse modulation schemes exist that allow separation of ambiguous ranges in Doppler space, allowing easy filtering of problematic ambiguous ranges.
Date: September 1, 2006
Creator: Doerry, Armin Walter
Partner: UNT Libraries Government Documents Department

Modeling femtosecond pulse propagation in optical fibers.

Description: Femtosecond pulse propagation in optical fibers requires consideration of higher-order nonlinear effects when implementing the non-linear Schroedinger equation. We show excellent agreement of our model with experimental results both for the temporal and phase features of the pulses. Ultrafast pulse propagation in optical fibers presents a number of challenges given the effect of nonlinearities which become important on such a short time scale. The modeling of femtosecond pulse propagation becomes, consequently, a harder task which has to account for all these effects. In this work, we have included higher order corrections in the non-linear Schroedinger equation and compared the numerical simulation results with experimental data. Our work, besides taking into account the temporal evolution of the pulse, keeps into account also the phase behavior of the electric field, which we compare with experimental results obtained with Frequency Resolved Optical Gating [l]. We also account for self-frequency shift of the pulse and obtain excellent agreement with the experimental results on the Raman shift.
Date: January 1, 2001
Creator: Chung, Y. J. (Yeo-Jin); Schaefer, T. B. (Tobias B.); Gabitov, I. R. (Ildar R.); Omenetto, F. G. (Fiorenzo G.) & Taylor, Antoinette J.,
Partner: UNT Libraries Government Documents Department

Nonlinear generation of very high order UV modes in microstructured fibers pumped with femtosecond oscillator.

Description: We report generation of high-order spatial modes in the UV range through nonlinear frequency conversion of the femtosecond 800 nm radiation in microstructured fibers. The process is distinct from Supercontinuum generation and is sensitive to fiber tip morphology. One of the manifestations of the unusual nonlinear properties of the microstructured (PCF) fibers is the robust supercontinuum generation from a few centimeters of the fiber with femtosecond oscillator pumping around 800 nm. Even though the fiber can be multimode at wavelengths down to the fundamental, supercontinuum is usually observed exiting the fiber in the fundamental mode. Recent experiments, however, evidenced the existence of other nonlinear effects in PCFs indicating critical role of phase matching between various spatial modes of the fiber. When the PCF is pumped by the 1550 nm femtosecond pulses, distinct visible bands are generated at the output belonging to distinct spatial modes of the fiber. Here we report that similar nonlinear mechanism exists when PCF is pumped by Ti:Sapphire femtosecond oscillator near 800 nm central wavelength. In this case, however, higher-order modes are generated in the UV range with observed wavelengths up to 310 nm, Fig. 1. Moreover, the effect is observed only when the input tip of the fiber has a non-flat surface, that is freshly cleaved fiber is prepared by melting the tip as described. The experiment consists of a femtosecond oscillator delivering 150-fs pulses with average power of up to 1.3 W to the fiber tip. After the attenuator, Faraday isolator and polarization control optics, the light is focused on the tip of the PCF with an aspheric lens. The fiber was a high-air-filling fraction single strand fused silica suspended by a honeycomb web of silica pellicles running along the length of the fiber, which was a few tens of centimeters in our experiments. The ...
Date: January 1, 2002
Creator: Efimov, A. V. (Anatoly V.); Omenetto, F. G. (Fiorenzo G.); Taylor, Antoinette J.,; Knight, J. C. (Jonathan C.); Wadsworth, W. J. (William J.) & Russel, P. S. J. (Philip St. J.)
Partner: UNT Libraries Government Documents Department

Development of a Fast High-Power Pulser and ILC DR Injection/Extraction Kicker

Description: Kicker is an efficient HOM power extractor. Peak HOM voltage and average power at the feeder may be sufficient to act on the kicker pulser. Feeder imperfections (real cable, feedthroughs, kicker electrodes, loads) is one source of residual energy between bunches. HOM spectrum is broad.
Date: October 16, 2007
Creator: Krasnykh, A.
Partner: UNT Libraries Government Documents Department

Approaches to instrument design at pulsed neutron sources

Description: A number of tools are used in the design of scattering instruments for pulsed neutron sources. Initial design is based largely on simple analytical calculations. More complicated analytical calculations and Monte Carlo simulations come into play as the design is optimized to maximize the data rate and to improve the data quality. Examples are used to illustrate the relative roles of these different computational tools. Areas are also identified where appropriate computational tools are currently lacking.
Date: April 14, 1997
Creator: Crawford, R.K.
Partner: UNT Libraries Government Documents Department

Induction linacs and pulsed power

Description: Progress in electronic power conversion technology is making possible a new class of induction linacs that can operate at extremely high repetition rates. Advances in insulator technology, pulse forming line design and switching may also lead to a new type of high current accelerator with accelerating gradients at least an order of magnitude greater than those attainable today. The evolution of the induction accelerator pulsed power system will be discussed along with some details of these emerging technologies which are at the frontiers of accelerator technology.
Date: July 11, 1995
Creator: Caporaso, G.J.
Partner: UNT Libraries Government Documents Department

Modeling of thermal, electronic, hydrodynamic, and dynamic deposition processes for pulsed-laser deposition of thin films

Description: Various physical processes during laser ablation of solids for pulsed-laser deposition (PLD) are studied using a variety of computational techniques. In the course of the authors combined theoretical and experimental effort, they have been trying to work on as many aspects of PLD processes as possible, but with special focus on the following areas: (a) the effects of collisional interactions between the particles in the plume and in the background on the evolving flow field and on thin film growth, (b) interactions between the energetic particles and the growing thin films and their effects on film quality, (c) rapid phase transformations through the liquid and vapor phases under possibly nonequilibrium thermodynamic conditions induced by laser-solid interactions, (d) breakdown of the vapor into a plasma in the early stages of ablation through both electronic and photoionization processes, (c) hydrodynamic behavior of the vapor/plasma during and after ablation. The computational techniques used include finite difference (FD) methods, particle-in-cell model, and atomistic simulations using molecular dynamics (MD) techniques.
Date: November 1, 1994
Creator: Liu, C.L.; LeBoeuf, J.N.; Wood, R.F.; Geohegan, D.B.; Donato, J.M.; Chen, K.R. et al.
Partner: UNT Libraries Government Documents Department