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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Investigation and characterization of a high energy piezoelectric pulse

Pinkston, Caroline Susan. January 2005 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (December 18, 2006) Includes bibliographical references.
12

Bipolêre pulsers vir die aandrywing van hoë drywing hoë herhalingstempo pulslasers

Tromp, Henry Teeton Wickens 03 April 2014 (has links)
M.Ing. (Electrical And Electronic Engineering) / The theme of this thesis is the time compression of energy in electrical systems with the aim of improving the efficiency and average power throughput capability of existing pulse compression systems. Recent success in the design of pulse lasers indicated successful operation at repetition rates of up to 2kHz, demanding more powerful pulse power supplies. These pulse lasers require unusually high peak power, not obtainable with conventional switching techniques. Typical pulse voltages of up to 40kV with peak currents of lOkA and rise times of 150ns are required. Traditionally thyratrons have been used for this application, but the limited lifetime of these devices is a major shortcoming, especially when operating at 2kHz. New switching techniques were needed. Excellent results have been obtained using saturable inductors as magnetic switches in pulse compressors, but notwithout limitations. The generation of heat due to core losses tends to limit the power throughput capability of these compressors, especially in the final stages. The minimisation of these losses is therefore of utmost importance. In order to improve the current systems, a study of the basic principles of compression was conducted. Loss-mechanisms, especially in the magnetic components, were modelled with the object of minimising losses. The limitations imposed on the system by flux conservation in magnetic and dielectric materials, led to the development of the new concept of bipolar compression. A full-scale bipolar compressor and pulse power supply was constructed and experimental results on this system are presented, showing an improvement in the efficiency. A new method for designing pulse compressors, incorporating core losses,evolved from this development
13

Projeto, construção e caracterização de um modulador pulsado para a operação de uma válvula magnetron de potência

CARLETO, NIVALDO 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:50:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:56Z (GMT). No. of bitstreams: 1 10558.pdf: 10529307 bytes, checksum: be6b9ffcdd1b8416d5246549ff0f8d3d (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
14

Projeto, construção e caracterização de um modulador pulsado para a operação de uma válvula magnetron de potência

CARLETO, NIVALDO 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:50:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:56Z (GMT). No. of bitstreams: 1 10558.pdf: 10529307 bytes, checksum: be6b9ffcdd1b8416d5246549ff0f8d3d (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
15

The tunnel diode monostable multivabrator

Morgan, Max Joseph, 1037- January 1961 (has links)
No description available.
16

Linear and nonlinear optical pulse characterisation

Finch, Andrew January 1989 (has links)
Developmental work on the generation and measurement of ultrashort pulses has been performed. A colliding pulse, passively mode-locked (CPM) ring dye laser has been investigated by spectral analysis and the nonlinear technique of second harmonic generation autocorrelation. Two systems for the intracavity compensation of group velocity dispersion (GVD) have been experimentally compared in the CPM laser. Initially one scheme, utilising Gires-Toumois interferometers, has achieved pulse durations of 64 fs. A second technique employing a four-prism sequence within the cavity gave typical pulse durations of -40 fs and focussing adjustments within the jets achieved durations as short as 19 fs for the first time. A realtime interferometric autocorrelator was constructed and detailed theoretical work has been performed to model the resultant fringe resolved autocorrelations as a function of pulseshape and frequency chirp. Spectral and autocorrelation analysis of the CPM laser led to the inference that the laser pulse intensity profiles were distinctly asymmetric. The main sources of frequency chirp within the laser cavity were assessed in order to find possible explanations for this type of laser behaviour. The linear pulse measurement technique employing synchroscan streak cameras was also critically assessed in terms of the available temporal resolutions as a function of phase noise in the RF deflection signal. Two streak tube designs, the Photochron II and the Photochron IV, have been experimentally compared employing the CPM laser as a test pulse source. Optimisation of the synchronisation circuitry has allowed the notable achievement of a temporal resolution of 0.93ps for the Photochron IV streak camera. A computer-interfaced readout system incorporating a charge coupled device (CCD) sensor has been developed which allows the recording of synchroscan streak events with a digitisation accuracy up to 12 bits. Preliminary experimentation was also performed to investigate the feasibility of incorporating a electron sensitive CCD structure within the envelope of the streak camera. It is intended that such a streak camera will be incorporated in a spaceborne laser ranging system and a theoretical assessment of the expected instrument performance has been performed. The above investigations have direct relevance to other types of ultrashort pulse sources and their application in optical communications, time-resolved spectroscopy and ultrafast electrooptic sampling.
17

A solid circuit for generating ultra-wide pulses

Miller, James Edward January 1962 (has links)
No description available.
18

Instrumentation for an election beam plasma system

Hagedon, Gary Lee, 1950- January 1975 (has links)
No description available.
19

A programmable pulse generator for in-vitro neurophysiologic experiments /

Licari, Frank. January 2007 (has links)
Thesis (M.S.)--University of Toledo, 2007. / Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science in Bioengineering." Bibliography: leaves 152-154.
20

High spatial and spectral quality diode-laser-based pump sources for solid-state lasers and optical parametric oscillators

Lindsay, Ian D. January 1999 (has links)
In this thesis the use of high spatial- and spectral-quality diode-laser pump sources for solid-state lasers and continuous-wave optical parametric oscillators (cw OPOs) is investigated. While diode lasers are potentially attractive, compact, low-cost pump sources for solid-state lasers and cw OPOs, the difficulty in obtaining moderate output powers, while retaining high spatial beam quality and spectral purity, often limits the potential of such lasers in these applications. Techniques for obtaining high-power, high spatial- and spectral-quality output from diode lasers are reviewed and the design, development and characterisation of an injection-locked broad-area diode-laser system is described. This system produced output powers of &ap;400mW in a near-diffraction-limited beam (M2&ap;w1.3) and with a spectral width of < 30MHz. The injection-locked system was used as the pump source for a quasi-three-level 946-nm Nd:YAG laser. End-pumped solid-state lasers of this type can offer potentially efficient, low-threshold operation if a near-diffraction limited pump source is used allowing optimal overlap with the laser mode. A model, including pump beam quality effects, is developed for such lasers and used to highlight the advantages of a near- diffraction-limited pump source, especially in the case of the 946-nm Nd:YAG transition which suffers from low gain and significant reabsorption losses. A 946-nm Nd: YAG laser pumped by the injection-locked system is described, yielding cw output powers up to 120mW with a 46% slope efficiency, performance comparable to Ti:sapphire- or dye-laser pumping, and 27ns Q-switched pulses having peak powers of 180W. 50W, 20ns pulses at 473nm were obtained by second-harmonic generation in KNbOs. The performance and relative merits of various cw OPO configurations, in the context of diode-laser pumping, are discussed and the development of a doubly- resonant OPO (DRO) based on periodically-poled lithium niobate is described. When pumped by the injection-locked system, this device showed a threshold of 25mW and .tuning of the outputs over 1.15- 1.25 mum at the signal and 2.3-2.65 mum at the idler was obtained by variation of crystal temperature, PPLN grating period and pump wavelength. When pumping with a 100mW single-mode diode laser, a 15mW OPO threshold was observed while retaining a similar tuning range. This represented the first demonstration of a cw DRO directly pumped by a single-mode diode laser. The achievement of such spectral coverage while pumping with this source points to the potential of such systems as compact, tunable sources in the near-to mid-infrared.

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