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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.
1

Inductively Loading a Half Width Leaky Wave Antenna to Control the Main Beam Direction

Corwin, Michael Thomas 21 August 2012 (has links)
No description available.
2

An?lise dos Modos Ressonantes em Antenas de Microfita sobre Substratos Iso/Anisotr?picos por T?cnicas da Resson?ncia Transversa

Silva, Jefferson Costa e 20 December 2005 (has links)
Made available in DSpace on 2014-12-17T14:55:01Z (GMT). No. of bitstreams: 1 JeffersonCS.pdf: 1778652 bytes, checksum: 9c7b8596078955525164e6707b6830eb (MD5) Previous issue date: 2005-12-20 / Neste trabalho, s?o utilizadas a T?cnica da Resson?ncia Transversa (TRT) e a T?cnica da Resson?ncia Transversa Modificada (MTRT), para a determina??o das freq??ncias dos modos ressonantes de antenas de microfita com patch quadrado, retangular e circular e com substratos isotr?picos e anisotr?picos. Para isso, ? proposto um modelo da cavidade equivalente, onde a antena tipo patch retangular ? representada como sendo a superposi??o de duas linhas infinitas em microfita, uma de largura W, representando a dimens?o que expressa a largura do patch, e a outra com largura L, representando a dimens?o que expressa o comprimento do patch. A avalia??o da efici?ncia e aplicabilidade dos m?todos citados ? realizada comparando-se com resultados experimentais e obtidos atrav?s de outras t?cnicas. Tr?s situa??es ser?o verificadas: estruturas com substrato infinito, estrutura com substrato tipo pedestal e estruturas com substrato truncado al?m dos limites da fita met?lica. Os resultados obtidos demonstram que as t?cnicas de an?lise de onda completa utilizadas neste trabalho, por um formalismo matem?tico mais rigoroso, s?o eficientes e precisas tanto na aplica??o em estruturas com substrato isotr?pico como nas que possuem substrato anisotr?pico. Inicialmente s?o consideradas apenas as estruturas com substratos isotr?picos, com diferentes constantes diel?tricas, e ? avaliada a influ?ncia da largura do substrato sobre as freq??ncias dos modos ressonantes das antenas. Posteriormente, a an?lise do truncamento do diel?trico ? realizada para estruturas com substrato anisotr?pico. Em todos os casos, os resultados experimentais, obtidos a partir da constru??o de prot?tipos, s?o confrontados com os obtidos a partir de simula??o, utilizando as t?cnicas TRT e MTRT. No final, as t?cnicas descritas s?o utilizadas para antenas tipo patch circular, sendo utilizada uma t?cnica de equival?ncia para transformar a antena circular em outra quadrada ou retangular equivalente, dependendo do modo que se queira encontrar. Os resultados obtidos s?o ent?o analisados, observando-se uma boa concord?ncia e indicando a viabilidade do m?todo. Ap?s isso, s?o apresentadas as conclus?es e sugeridos alguns temas para a continuidade deste trabalho
3

Caracteriza??o de estruturas planares com substratos Iso/Anisotr?picos truncados atrav?s da t?cnica da resson?ncia transversa modificada

Carvalho, Joabson Nogueira de 19 December 2005 (has links)
Made available in DSpace on 2014-12-17T14:55:00Z (GMT). No. of bitstreams: 1 JoabsonNC.pdf: 1023745 bytes, checksum: 5c279305bf7356a4d77b64ca8e0c6261 (MD5) Previous issue date: 2005-12-19 / This work presents a theoretical and numerical analysis using the transverse resonance technique (TRT) and a proposed MTRT applied in the analysis of the dispersive characteristics of microstrip lines built on truncated isotropic and anisotropic dielectric substrates. The TRT uses the transmission lines model in the transversal section of the structure, allowing to analyze its dispersive behavior. The difference between TRT and MTRT consists basically of the resonance direction. While in the TRT the resonance is calculated in the same direction of the metallic strip normal axis, the MTRT considers the resonance in the metallic strip parallel plane. Although the application of the MTRT results in a more complex equivalent circuit, its use allows some added characterization, like longitudinal section electric mode (LSE) and longitudinal section magnetic mode (LSM), microstrips with truncated substrate, or structures with different dielectric regions. A computer program using TRT and MTRT proposed in this work is implemented for the characterization of microstrips on truncated isotropic and anisotropic substrates. In this analysis, propagating and evanescent modes are considered. Thus, it is possible to characterize both the dominant and higher order modes of the structure. Numerical results are presented for the effective permittivity, characteristic impedance and relative phase velocity for microstrip lines with different parameters and dimensions of the dielectric substrate. Agreement with the results obtained in the literature are shown, as well as experimental results. In some cases, the convergence analysis is also performed by considering the limiting conditions, like particular cases of isotropic materials or structures with dielectric of infinite size found in the literature. The numerical convergence of the formulation is also analyzed. Finally, conclusions and suggestions for the continuity of this work are presented / Este trabalho apresenta os fundamentos te?ricos da t?cnica da resson?ncia transversa (TRT) e da t?cnica da resson?ncia transversa modificada (MTRT) aplicada na an?lise das caracter?sticas dispersivas de uma microfita considerando substratos diel?tricos isotr?picos e anisotr?picos truncados. A TRT utiliza o modelo da linha de transmiss?o na se??o transversal da estrutura, permitindo analisar o seu comportamento dispersivo. A diferen?a entre a TRT e MTRT consiste basicamente na dire??o da resson?ncia. Enquanto na TRT a resson?ncia ? calculada ao longo do eixo normal ? fita met?lica, a MTRT considera a resson?ncia no plano paralelo ? fita met?lica. Embora a aplica??o da MTRT resulte num circuito equivalente mais complexo, sua utiliza??o permite a caracteriza??o mais precisa, incluindo modo el?trico de se??o longitudinal (LSE) e modo magn?tico de se??o longitudinal (LSM), microfitas com substrato truncado, ou estruturas planares com multiplas regi?es diel?tricas. Um programa computacional utilizando a TRT e MTRT ? discutido e desenvolvido para caracteriza??o de microfitas sobre substratos isotr?picos e anisotr?picos truncados. Na an?lise, consideram-se modos propagantes e evanescentes. Assim, ? poss?vel caracterizar n?o somente o modo fundamental, mas tamb?m os modos de ordem superior da estrutura. S?o apresentados resultados num?ricos para as diversas grandezas, ou seja, permissividade efetiva, imped?ncia caracter?stica e velocidade de fase relativa para microfita com diferentes par?metros e dimens?es do substrato. S?o feitas compara??es com outros resultados dispon?veis na literatura e, tamb?m, com resultados determinados experimentalmente. Em alguns casos, os resultados s?o comparados como casos particulares de materiais isotr?picos ou de estruturas com diel?tricos de tamanho infinito encontradas na literatura, tendo sido observada uma excelente concord?ncia. Apresenta-se, ainda, um estudo de converg?ncia da formula??o proposta e, finalmente, conclus?es e sugest?es para continuidade do trabalho
4

Transverse Resonance Island Buckets in Advanced Light Sources

Arlandoo, Michael Etienne 18 October 2024 (has links)
Transverse Resonance Island Buckets (TRIBs) ist eine spezielle Einstellung der strahlführenden Magnetoptik eines Speicherrings nahe einer nichtlinearen Resonanz, die einen zweiten vom Hauptorbit gut getrennten und stabilien Orbit erzeugt. Dieser Inselorbit ist verknüpft mit zusätzlichen Potentialtöpfen im transversalen Phasenraum, in denen ebenfalls Elektronen gespeichert werden können. Wird der Speicherring als Synchrotronstrahlungsquelle genutzt, so können den Experimentatoren durch die zwei stabilien Orbits zwei unterschiedliche Lichtquellen mit z.B. unterschiedlichen Pulswiederholungsraten angeboten werden. Diese Dissertation untersucht, ob man die TRIBs Einstellung mit der deutlich komplizierteren und nichtlinear anspruchsvolleren Multi-Bend-Achromat (MBA) Magnetoptik einer vierten Generation Synchrotronstrahlungsquelle zusammen bringen kann. Ein resonanter Hamiltonian in der Nähe einer horizontalen Resonanzen dritter Ordnung, die von Sextupolen getrieben wird, abgeleitet. Dieser Hamiltonian enthält drei Parameter, die den TRIBs-Phasenraum vollständig definieren, nämlich den Abstand des Arbeitspunktes zur Resonanz, die Resonanzstärke und den "detuning-Parameter", der beschreibt wie die Resonanz auf Teilchen mit unterschiedlichen Amplituden wirkt. Durch die analytische Betrachtung der Resonanzstärke in Hinblick auf die entscheidenden Größen der Magnetoptik, d.h. die Twiss-Optikfunktionen und die Sextupolstärken zeigt sich ein unterschiedliches TRIBs verhalten für systematischen Resonanzen und nicht-systematische Resonanzen. Bei nicht-systematischen Resonanzen muss die Periodizität der Magentoptik gestört werden um TRIBs zu erzeugen. Bei systematischen Resonanzen, muss der Arbeitspunkt sowohl des Rings als auch seiner sich wiederholenden periodischen Einheitszelle die Resonanzbedingung dritter Ordnung erfüllen um TRIBs zu erzeugen. / Transverse resonance island buckets (TRIBs) is a special accelerator optics mode where the storage ring is tuned close to a nonlinear resonance and this results in the production of a secondary stable orbit, well separated from the main one. This orbit corresponds to islands in transverse phase space and it can be filled with bunches independently from the main orbit to some extent. This thesis investigates the possibility of implementing the TRIBs mode in the multi-bend achromat (MBA) lattice candidates of BESSY III right from the beginning when strong nonlinearities due to sextupole magnets are present. A resonant Hamiltonian is derived using the perturbative techniques of nonlinear dynamics, valid close to third-order horizontal resonances. This Hamiltonian contains three parameters that fully determine the structure of the phase space with islands namely the distance from the resonance in tune space, the resonance strength, and the detuning, a parameter that gives the rate at which particles with different amplitudes hit the resonance. By calculating the resonance strength analytically in terms of the lattice quantities such as the Twiss functions and the sextupole strengths, two types of resonances are revealed in a transparent manner and it is shown that close to these third-order resonances, islands can be established. The first one is the random resonance where the periodicity of the lattice needs to be broken to have islands. The need for a periodicity breaking is proved explicitly. The second type is the systematic resonance where the tunes of both the ring and its superperiod (repeating unit) need to satisfy a third-order resonance condition. These two types of resonances are studied and compared in detail and the stability of the two BESSY III lattice candidates with respect to TRIBs is discussed.
5

Transverse Resonance Island Buckets at BESSY II / A new Bunch Separation Scheme

Armborst, Felix 03 February 2022 (has links)
Die steigende Nachfrage nach Synchrotronstrahlungsanlagen hat zu einem stetig wachsenden Angebot auf der ganzen Welt geführt. Die wissenschaftliche Nutzergemeinde der Speicherring-basierten Lichtquellen benötigt immer höhere Brightness und viele sind auch an speziellen Zeitstrukturen der Strahlung, wie kurzen Pulslängen und bestimmten Wiederholungsraten, interessiert. Dies hat zu einer kontinuierlichen Verbesserung bestehender und zum Bau vieler neuer Anlagen geführt. Das Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) betreibt den Berlin Electron Storage Ring Society for SYnchrotron Radiation (BESSY) II, eine Lichtquelle dritter Generation. Der Betrieb der Speicherring basierten Lichtquelle BESSY II nahe der transversalen, optischen Resonanz dritter Ordnung mit Transverse Resonance Island Buckets (TRIBs) Optik ermöglicht die Speicherung von Strom auf einer zweiten, stabilen Umlaufbahn. Der zweite Orbit windet sich im transversalen x-x′-Phasenraum über drei Umläufe um den Kernorbit und hat somit etwa den dreifachen Arbeitspunkt des Kernstrahls. Der stabile Inselorbit bietet die Möglichkeit, die Elektronen für jeden der 400, von der 500 MHz BESSY II Radio Frequency (RF) Kavität definierten, Buckets, fast beliebig zwischen dem Kern und den drei zugehörigen TRIBs zu verteilen. Dies eröffnet neue Möglichkeiten der Bunchtrennung. Durch Bevölkerung eines Orbits mit wenigen Elektronenpaketen, kann dieser dediziert für zeitaufgelöste Experimente genutzt werden. Es erhalten alle Strahlrohre mit hinreichender Akzeptanz die Möglichkeit, zeitaufgelöste Experimente durchzuführen. Die Bunchtrennung wird durch Ausrichtung der Strahlrohre auf den gewünschten Orbit erreicht. Somit stellt dieser Betriebsmodus eine Möglichkeit dar, die Timing-Fähigkeiten der BESSY II-Anlage und Speicherringbasierter Lichtquellen im Allgemeinen weiter auszubauen. / The increasing demand for synchrotron radiation facilities has led to a continuously increasing offer around the world. The scientific user community of storage-ring-based light sources requires ever-higher brightness and many are also interested in special time structures of the radiation such as short pulse lengths and certain repetition rates. This has led to continuous upgrades of existing and the construction of many new machines around the world. The Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) operates the third generation light source Berlin Electron Storage Ring Society for SYnchrotron Radiation (BESSY) II. Operation of the storage-ring-based light source BESSY II in proximity of the third-order, transverse, optical tune resonance with Transverse Resonance Island Buckets (TRIBs) optics enables storage of current on a second stable orbit winding around the core orbit in the transverse x-x′ -phase space. This second orbit closes after three revolutions, resulting in a tune approximately three times that of the core tune. The stable island orbit provides the possibility to populate each of the 400 Radio Frequency (RF) buckets, defined by the 500 MHz cavities at BESSY II not only on the core but also additionally or exclusively on one or all three of the corresponding transverse island buckets of the threefold island orbit. This provides unique bunch separation possibilities with the appropriate population of each orbit. The population of one orbit with single bunches enables dedicated utilisation of this orbit for timing experiments and gives all beamlines with sufficient acceptance access to time-resolved experiments. The bunch separation is realised by aligning each beamline with the desired orbit. Thus, this operation mode represents a possibility to enhance the timing capabilities at BESSY II and storage ring based light sources in general.

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