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Dissertations / Theses on the topic 'Traveling-wave tubes'
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Zuboraj, MD R. "Coupled Transmission Line Based Slow Wave Structures for Traveling Wave Tubes Applications." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1477947681829031.
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Birtel, Philip [Verfasser]. "Inclusion of Multi-Reflections in the Beam-Wave Interaction Simulation of Traveling Wave Tubes / Philip Birtel." München : Verlag Dr. Hut, 2011. http://d-nb.info/1013526538/34.
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Safi, Djamschid [Verfasser]. "Simulation of traveling-wave tubes for analysis and optimization in modulated back-off / Djamschid Safi." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2020. http://d-nb.info/1217326774/34.
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Meyne, Sascha [Verfasser], and Arne F. [Akademischer Betreuer] Jacob. "Simulation and design of traveling-wave tubes with folded-waveguide delay lines / Sascha Meyne ; Betreuer: Arne F. Jacob." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2017. http://d-nb.info/112872667X/34.
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Meyne, Sascha [Verfasser], and Arne [Akademischer Betreuer] Jacob. "Simulation and design of traveling-wave tubes with folded-waveguide delay lines / Sascha Meyne ; Betreuer: Arne F. Jacob." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2017. http://nbn-resolving.de/urn:nbn:de:gbv:830-88215541.
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Park, Jongwoon Huang W. P. "Modeling, simulation and performance optimization of wideband semiconductor optical amplifiers." *McMaster only, 2004.
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Theveny, Stéphane. "Approches fréquentielle et temporelle de la dynamique des tubes à onde progressive." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4741.
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Le tube à onde progressive (TOP) est un dispositif où un faisceau d’électrons se déplaçant sur l’axe d’une hélice interagit avec les ondes électromagnétiques propagées par cette hélice. Il est le siège de nombreuses instabilités : des oscillations (génération d’ondes hyperfréquences parasites), mais aussi des instabilités du faisceau qui ont pour conséquence une dissipation parasite due à l'interception du faisceau par l'hélice. L’objectif de cette thèse est de développer une formulation hamiltonienne au problème permettant des modèles approchés plus compacts, plus précis et plus complets. Après l'avoir exposée, nous présentons un schéma numérique contenant notre modèle discret pour la simulation du TOP. Ce modèle discret a été mis au point pour tenir compte des conditions d'adaptation et de changements de géométrie. Le couplage avec les électrons met en jeu des champs de base simples, et le modèle tient compte de la charge d'espace. Différentes méthodes d'intégration numérique sont développées, dont nous comparons l'efficacité. Nous comparons ce modèle discret avec divers modèles d'amplification des ondes à froid, dont le modèle actuellement utilisé chez Thales pour la conception des tubes ({texttt{MVTRAD}}). Nous montrons aussi que les modèles d'amplification des ondes à froid à deux ou trois dimensions comme {texttt{MVTRAD}} ou {texttt{BWIS}} (prenant en compte les ondes inverses) ne respectent pas nécessairement l'équation de Maxwell-Faraday, contrairement au nôtre. Enfin, nous comparons notre modèle discret de circuit et le modèle d'amplification des ondes à froid dans le cas d'un faisceau linéaireA traveling-wave tube (TWT) is a device where an electron beam traveling along the axis of a helix interacts with the electromagnetic waves propagated by this helix. It is sensitive to many instabilities : oscillators (generating noise microwave), but also beam instabilities that generate a noise dissipation due to the interception of the beam by the helix. The aim of this thesis is to find a Hamiltonian formulation of the problem to allow more compact, more accurate and more complete approximate models. Having found one, we start to develop a numerical scheme containing our discrete model for the simulation of TOP. This discrete model has been developed to take into account the tapering sections, geometry changes and adaptations. The coupling with electrons involves simple functions of space, and the model takes space charge into account. Different methods of numerical integration are developed, of which we compare the efficiency. We compared the discrete model with various cold waves amplification models, especially with the model currently used at Thales for the design of their tubes ({texttt{MVTRAD}}). Moreover, we showed that two- or three-dimensional cold wave amplification models like {texttt{MVTRAD}} or {texttt{BWIS}} (which takes into account the backward waves) fail to respect the Maxwell-Faraday equation, contrary to ours. Finally we made a comparison between our circuit discrete model and the amplification model of cold waves in the case of a linear beam
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Chbiki, Mounir. "Caractérisation thermomécanique des lignes de transmission et des collecteurs dans les tubes à ondes progressives." Thesis, Paris 10, 2014. http://www.theses.fr/2014PA100168/document.
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Durant ces quarante dernières années, les Tubes à Ondes Progressives (TOP) n’ont cessé de se développer, orienté par la demande croissante des nouvelles applications (Internet Haut débit, TV HD…). Cette demande croissante en fréquence et en puissance se traduit par des problèmes d’échauffement thermique. En effet, l’augmentation de la puissance de sortie augmente la puissance dissipée. De plus, la montée en fréquence nécessite une diminution des dimensions, qui conduit tout logiquement à des densités de puissance plus importantes. Cette chaleur produite doit être évacuée par des petites surfaces de contact qui dépendent fortement du type d’assemblage. Cet échauffement thermique implique également des changements du comportement mécanique. Dans ce travail de thèse, le point principal a été l’étude du comportement des interfaces dans les tubes à ondes progressive. Il est question d’étudier les interfaces thermomécaniques produites lors de l'assemblage (frettage à chaud). L’objectif est de fournir un modèle de détermination de la température d’hélice en fonctionnement. Compte tenu des configurations de fonctionnement (Vide, haute tension, petite dimension…) une mesure directe n’est pas réalisable. Néanmoins plusieurs méthodes de mesure indirectes ont été investiguées afin de trouver la plus appropriée. Cette étude porte dans un premier temps sur les lignes de transmissions puis sur les collecteurs des TOPs. Nous avons réalisé un modèle analytique purement thermique permettant d’identifier rapidement l’impédance thermique des dispositifs. Une mesure de RTC et une coupe métallographique déterminant les surfaces de contact alimente ce modèle afin de lui donner une meilleure précision. Un modèle élément finis 2D nous permet d’identifier une pression moyenne de contact afin d’utiliser la RTC correspondante.L’impédance thermique, nous permet de trouver la température d’hélice en indiquant la puissance dissipée dans la ligneDuring these last forty years traveling Waves tubes did not stop developing directed by the increasing request of the new applications (High-speed Internet, TV HD). This increasing request in frequency and in power is translated by thermal heating problems. Indeed, the more the output power will be high, the more there will be of the dissipated power, with smaller and smaller size. This leads logically to bigger and bigger power densities. This produced heat must be evacuated by small contact areas, which depend strongly on the type of assembly. This thermal heating also involves changes of the mechanical behaviour. The principal point will be the study of the behaviour of the interfaces in traveling waves tubes. Thesis work, we study the thermal and mechanical interfaces produced during a hot shrinking. Goal of this work is to supply a numerical or analytical model of helix temperature determination with functioning. Considering the configurations of functioning (Vacuum, high-voltage, small dimension) a direct measure is not impossible. Nevertheless several indirect measure methods were investigated to find the most appropriate. This study concerns at first the transmissions lines then the collectors of TOPS. We realized an analytical thermal model allowing to identify quickly the thermal impedance of devices. A thermal contact resistance measurement and a metallographic cutting determining the contact areas feeds this model to give it a better precision. A 2D finite element allows us to identify an average pressure of contact to use the corresponding RTC. The thermal resistance, allows us to find the helix temperature by indicating the power dissipated in the line
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Lopes, Daniel Teixeira. "Análise multi-sinal e caracterização experimental de válvulas de ondas progressivas (TWT) para aplicação em amplificadores de micro-ondas." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-03042012-093927/.
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Este trabalho apresenta o desenvolvimento de uma plataforma para o estudo teórico e experimental de dispositivos amplificadores de micro-ondas do tipo válvula de ondas progressivas (TWT). A plataforma é composta por um modelo matemático e uma bancada de testes. O modelo matemático descreve a TWT como uma linha de transmissão acoplada a um feixe eletrônico unidimensional, onde as forças de carga espacial AC e DC são calculadas auto consistentemente, eliminando-se a necessidade de um cálculo separado para o fator de redução de carga espacial. O modelo matemático deu origem a dois códigos para a simulação da TWT. Ambos foram comparados com resultados experimentais e teóricos disponíveis na literatura especializada para uma pré-validação. O nível de concordância entre os presentes resultados e aqueles de referência foi acima de 90%, o que atendeu as expectativas de exatidão do modelo, tendo em vista que nem todos os parâmetros de entrada estavam disponíveis na referência. A bancada de testes construída é composta por uma TWT com banda de operação de 6,0 a 18 GHz e potência saturada máxima em torno de 55 dBm (316 W) em 13 GHz, um circuito de polarização para a mesma e a instrumentação necessária para a realização das medidas pertinentes aos amplificadores de potência. A TWT em questão foi caracterizada segundo seu comportamento mono-sinal e multi-sinal. As curvas de ganho e potência foram obtidas em função da frequência utilizando a voltagem de aceleração do feixe eletrônico e a potência de entrada como parâmetros. As curvas de transferência de potência, de fase e compressão de ganho foram obtidas para frequências escolhidas ao longo da banda, tendo novamente a voltagem de aceleração como parâmetro. Adicionalmente, a produção de produtos de intermodulação de terceira ordem foi caracterizada no ponto de 1 dB de compressão de ganho ao longo da banda analisada. Um teste de linearização por injeção de sinais, que estava previsto no plano de trabalho, não apresentou o desempenho esperado devido a problemas no funcionamento do circuito linearizador. Esses problemas foram analisados e listou-se uma série de passos para saná-los.This work deals with the development of a platform for theoretical and experimental investigations of microwave amplifiers devices of the type traveling-wave tube (TWT). The platform consists of a mathematical model and a test bench. The mathematical model describes the TWT as a transmission line coupled to a onedimensional electron beam, in which the AC and DC space charge forces are calculated self-consistently, eliminating the need for a separate calculation for the space charge reduction factor. The mathematical model gave rise to two codes for the simulation of TWTs. Both codes were validated against experimental and theoretical results available in the literature. The overall level of agreement between the present results and those from the reference was above 90%, which was considered satisfactory since not all input parameters were available in the reference. The test bench consists of a wideband TWT operating from 6.0 to 18 GHz and maximum saturated power around 55 dBm (316 W) at 13 GHz, a biasing circuit, and the instrumentation needed to perform the relevant measurements to the power amplifier. The TWT in question was characterized according to its mono-signal and multi-signal behavior. The gain and power curves were obtained as a function of the frequency using the beam voltage and the input power as parameters. The curves of power transfer, phase transfer and gain compression were obtained for selected frequencies along the operating band, again, using the beam voltage as a parameter. Furthermore, the production of third-order intermodulation products was measured at the 1 dB gain compression point over the band analyzed. A linearization test applying the signal injection technique, which was part of the initial work plan, presented inadequate performance due to problems in the linearizer circuit operation. These problems were analyzed and a guide to solve them was provided.
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Menninger, Wiliam Libbey. "Relativistic harmonic gyration traveling-wave tube amplifier experiments." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36953.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 209-214).
by William Libbey Menninger.
Ph.D.
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Kowalski, Elizabeth J. (Elizabeth Joan). "Design and test of a 94 GHz overmoded traveling wave tube amplifier." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97805.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 175-180).
This thesis discusses the design and test of an overmoded W-band Traveling Wave Tube (TWT). The TWT was designed to operate in the rectangular TM31 cavity mode at 94 GHz. The unwanted lower order, TM₁₁ and TM₂₁, modes were suppressed using selectively placed aluminum nitride dielectric loading. Simulations in 3-D CST Particle Studio confirmed suppression of unwanted modes due to dielectric loading and operation in the TM31 mode. The TWT was designed to operate at 31 kV with 310 mA and a 2.5 kG solenoid magnet. Simulations in both 1-D Latte and 3-D CST predicted 32 dB of gain, 200 MHz bandwidth, and 300 W peak output power for the TWT at 94 GHz. Test structures of 9- and 19- cavities were made via CNC direct machining. Cold test measurements showed suppression of the unwanted modes and transmission of the TM₃₁ mode, which correlated well with HFSS simulations. Two final 87-cavity structures were built and cold tested. The experiment was designed and built in-house at MIT (with exception of the electron gun cathode, manufactured by industry). It was operated with a 3 microsecond pulsed power supply. A beam test was implemented which confirmed operation of the TWT set up and electron gun. The electron gun operated at 31 kV with 306+/-6 mA of current detected at the collector and 88 % transmission of current. Initial operation of the TWT showed zero-drive stable operation and demonstrated 8 dB of device gain and 10 W peak output power at 95.5 GHz. Following these first tests, the magnetic field alignment was improved and the second structure, which showed better circuit transmission in cold test, was installed. The overmoded TWT produced 21 2 dB device gain (defined as Pout/Pin) at 94.3 GHz and 27 W of saturated output power in zero-drive stable operation. The TWT was estimated to have about 6 dB of additional loss due to coupling into and out of the circuit. Taking that loss into account, the gain on the TWT circuit itself was estimated to be 27*/- 2 dB circuit gain. CST simulations for the experimental current and voltage predict 28 dB circuit gain, in good agreement with measurements. This experiment demonstrated the first successful operation of an overmoded TWT. The overmoded TWT is a promising approach to high power TWT operation at W-Band and to the extension of the TWT to terahertz frequencies.
by Elizabeth J. Kowalski.
Ph. D.
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Higashi, Cristiane. ""Investigação do processo de obtenção de aluminatos de bário e cálcio para construção e caracterização de catodos termiônicos impregnados para aplicação em dispositivos de microondas de potência"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-31052007-150633/.
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O presente trabalho descreve os processos de preparação do aluminato de bário e cálcio, material emissor de elétrons, empregados nos catodos do tipo impregnado para utilização em uma válvula de microondas do tipo TWT. Os catodos investigados constituem-se de uma pastilha de tungstênio porosa impregnada com aluminato de bário e cálcio com proporção molar 5:3:2. Para a síntese do aluminato, utilizaram-se três diferentes métodos: reação em estado sólido, precipitação e cristalização. A termogravimetria auxiliou na consolidação dos procedimentos de preparação dos aluminatos de modo a definir os parâmetros de pirólise/calcinação. Verificou-se que a técnica que apresentou melhores características de síntese foi o método da cristalização, pois esta apresentou uma menor temperatura de formação do aluminato (800ºC) em atmosfera oxidante (O2), quando comparada às técnicas de reação em estado sólido e de precipitação (temperatura de 1000ºC em atmosfera redutora H2). Utilizou-se o conceito da distribuição da função trabalho prática (PWFD) de Miram para a caracterização termiônica dos catodos impregnados. Empregando-se este método, foi possível traçar o perfil termiônico do catodo com aluminato de bário e cálcio. As curvas PWFD apresentaram a função trabalho média do catodo aluminato de, aproximadamente, 2,00 eV.In the present work it is described the barium calcium aluminate manufacture processes employed to produce impregnated cathodes to be used in a traveling-wave tube (TWT). The cathodes were developed using a tungsten body impregnated with barium and calcium aluminate with a 5:3:2 proportion (molar). Three different processes were investigated to obtain this material: solid-state reaction, precipitation and crystallization. Thermal analysis, thermogravimetry specifically, supported to determine an adequate preparation procedure (taking into account temperature, time and pirolisys atmosphere). It was verified that the crystallization showed a better result when compared to those investigated (solid-state reaction and precipitation techniques formation temperature is about 1000ºC in hydrogen atmosphere), whereas it presented the lower formation temperature (800ºC) in oxidizing atmosphere (O2). It was used the practical work function distribution theory (PWFD) of Miram to characterize thermionic impregnated cathode. The PWFD curves were used to characterize the barium-calcium aluminate cathode. PWFD curves shown that the aluminate cathode work function is about 2,00 eV.
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Wlodyka, Mark Jan. "An intermediate frequency predistortion linearizer for an earth station traveling-wave tube amplifier." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26341.
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In multicarrler single-channel-per-carrier (SCPC) communication system design, intermodulation distortion is often a limiting factor. The intermodulation distortion caused by the AM/AM and AM/PM conversion effect of the microwave transmit high power amplifier (HPA) can be reduced by applying linearization techniques. Various linearization techniques are reviewed and an appropriate scheme is selected for use with a SCPC earth station traveling-wave tube amplifier (TWTA). A nonlinear model based on the third-order distortion phase of a TWTA is used to develop a new linearizer design model. The amplitude and phase transfer characteristics of a 14 GHz TWTA were measured and the results used in the design of an intermediate frequency (IF) predistortion linearizer. The predistortion linearizer developed uses an antiparallel diode distortion generator in a parallel branch network. The linearizer circuit operates at an IF of 280 MHz preceding an upconverter stage and the 14 GHz TWTA.
The linearizer was tested with a 20 watt 14 GHz TWTA under two-tone, multicarrler, and noise loading conditions. The experimental linearizer circuit effectively reduced the intermodulation distortion over a considerable range of normal drive levels, providing a 3 dB decrease in output backoff while maintaining a third-order IMD performance of 25 dBc. The linearizer compares favourably with published results of similar predistortion linearizers designed for satellite applications, and shows potential for practical use in low cost Ku band SCPC earth stations.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Homer, Mark L. (Mark Louis). "A parametric model for reducing the manufacturing cost of the traveling wave tube." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/35459.
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Sun, Ruoci. "Comportement en grand temps et intégrabilité de certaines équations dispersives sur l'espace de Hardy Long time behavior of the NLS-Szegö equation Traveling waves of the quintic focusing NLS-Szegö equation Complete integrability of the Benjamin-Ono equation on the multi-soliton manifolds." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS111.
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On s'intéresse dans cette thèse à trois modèles d'équations hamiltoniennes dispersives non linéaires : l'équation de Schrödinger cubique défocalisante sur le cercle, filtrée par le projecteur de Szegö, qui enlève tous les modes de Fourier strictement négatifs (NLS--Szegö cubique), l'équation de Schrödinger quintique focalisante filtrée par le projecteur de Szegö sur la droite (NLS--Szegö quintique) et l'équation de Benjamin--Ono (BO) sur la droite. Comme pour les deux modèles précédents, l'équation de BO peut encore s'écrire sous la forme d'une équation de Schrödinger quadratique filtrée par le projecteur de Szegö. Ces trois modèles nous donnent l'occasion d'étudier les propriétés qualitatives de certaines ondes progressives, le phénomène de croissance des normes de Sobolev, le phénomène de diffusion non linéaire et certaines propriétés d'intégrabilité de systèmes dynamiques hamiltoniens. Le but de cette thèse est de comprendre l'influence des opérateurs de Szegö (non locaux) sur les équations de type Schrödinger, et d'adapter les outils liés à l'espace de Hardy sur le cercle et sur la droite. On applique aussi la méthode de forme normale de Birkhoff, l'argument de concentration--compacité, qui est précisé à travers le théorème de d'ecomposition en profils, et la transformée spectrale inverse pour résoudre ces problèmes. Dans le troisième modèle, la théorie de l'intégrabilité permet de faire le lien avec certains aspects algébriques et géométriquesWe are interested in three non linear dispersive Hamiltonian equations: the defocusing cubic Schrödinger equation filtered by the Szegö projector on the torus that cancels every negative Fourier modes, leading to the cubic NLS--Szegö equation on the torus; the focusing quintic Schrödinger equation, which is filtered by the Szegö projector on the line, leading to the quintic NLS--Szegö equation on the line and the Benjamin--Ono (BO) equation on the line. Similarly to the other two models, the BO equation on the line can be written as a quadratic Schrödinger-type equation that is filtered by the Szegö projector on the line. These three models allow us to study their qualitative properties of some traveling waves, the phenomenon of the growth of Sobolev norms, the phenomenon of non linear scattering and some properties about the complete integrability of Hamiltonian dynamical systems. The goal of this thesis is to investigate the influence of the Szegö projector on some one-dimensional Schrödinger-type equations and to adapt the tools of the Hardy space on the torus and on the line. We also use the Birkhoff normal form transform, the concentration--compactness argument, refined as the profile decomposition theorem, and the inverse spectral transform in order to solve these problems. In the third model, the integrability theory allows to establish the connection with some algebraic and geometric aspects
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Minenna, Damien F. G. "Modélisation hamiltonienne N-corps de l'échange de moment dans l'interaction onde-particule non-linéaire." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0328.
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On s'intéresse à l'interaction onde-particule au travers d'une description N-corps (souvent jugée difficile à mettre en œuvre à cause du nombre de degrés de libertés mis en jeu). Pour les guides d'ondes périodiques, nous employons une technique de réduction, appelée le "modèle discret", pour diminuer drastiquement le nombre de degrés de libertés. Notre hamiltonien est ré-exprimé avec le modèle discret pour obtenir une théorie N-corps auto-cohérente unidimensionnelle capable de décrire les effets non-linéaires (oscillations, piégeages et chaos) de l'interaction onde-particule en domaine temporel. De plus, notre théorie est validée analytiquement avec un modèle robuste de circuit équivalent. Nous étudions aussi une version tridimensionnelle de notre théorie reposant sur la géométrie hélicoïdale. Notre hamiltonien sert de base à la construction d'un intégrateur numérique symplectique. Cet algorithme est utilisé pour modéliser diverses géométries de tubes à ondes progressives. Une validation de notre algorithme est réalisée avec des mesures expérimentales. Notre algorithme permet aussi l'étude de ces tubes, notamment des effets non-linéaire ainsi que la distorsion de signaux de télécommunication. Finalement, nous montrons que, lorsque la vitesse de phase d'un champ électromagnétique n'est pas égale à la célérité de la lumière dans le vide, alors ce champ admet une quantité de mouvement mécanique et un moment conjugué distincts. Ce phénomène, au cœur de la controverse Abraham-Minkowski, n'avait été observé que dans les milieux diélectriques. Nous étendons sa portée aux guides d'ondes et aux plasmas et suggérons l'universalité de ce dilemmeWe investigate the wave-particle dynamics using an N-body description (often deemed impossible due to the number of degrees of freedom involved). For periodic waveguides, we use a model reduction, called the "discrete model", to drastically reduce the number of degrees of freedom. This technique enables us to obtain smooth coupling terms, enabling the use of macro-particles. Our hamiltonian is reformulated with the discrete model to obtain a one-dimensional N-body self-consistent theory able to describe non-linear effects (oscillations, trapping and chaos) of the wave-particle interaction in time domain. Moreover, our theory is validated analytically against a robust equivalent circuit model. We also investigate a tridimensional version of our theory resting on the helix geometry. Our hamiltonian provides the basis to build a numerical symplectic integrator. This algorithm is used to simulate several traveling-wave tube geometries. Our algorithm is benchmarked against experimental measurements. It also allows the investigation of nonlinear effects in tubes as well as the analysis of the distortion of telecommunication signals. Finally, we demonstrate that, when the phase velocity of an electromagnetic field is not equal to the speed of light in vacuum, then this field has distinct kinematic and canonical momenta.This phenomenon, at the heart of the Abraham-Minkowski controversy, was only observed in dielectric materials so far. We extend its scope to vacuum waveguides and to plasmas, and we suggest its universality
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Sumathy, M. "Analysis Of Broad-band And High-Efficiency Folded-Waveguide Slow-Wave Structure For Millimeter-Wave Traveling-Wave Tubes." Thesis, 2011. https://etd.iisc.ac.in/handle/2005/2372.
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Vacuum microwave tubes, such as klystron, traveling-wave tube, gyrotron are high efficiency devices, where the RF interaction structure facilitates efficient energy transfer from the kinetic energy of the high energy electron beam to the electromagnetic wave. Traveling-wave Tube is the most versatile microwave power amplifier widely used for terrestrial communication, radar and aerospace applications.
The waveguide based slow-wave structures like Millman, Karp, inter digital, grated waveguide, ring-plane, ring-bar, millitron and folded-waveguide structure gathered importance for application in millimeter-wave traveling-wave tubes. Among these millimeter-wave interaction structures, the folded-waveguide slow-wave structure became the most popular due to its robust structure, high power capability, low RF loss, simpler coupling, reasonably wide bandwidth and ease of fabrication for millimeter-wave to terahertz frequencies. Hence this thesis aims to analyse the folded-waveguide slow-wave structure for broad-banding and efficiency enhancement.
The existing approaches for the analysis of cold circuit parameters (dispersion and interaction impedance characteristics) of folded-waveguide slow-wave structure are reinvestigated and found that these have limitation, as the effects of E-plane bend and beam-hole discontinuities are ignored in the parametric analysis. A cascaded matrix equivalent circuit model includes the effect of E-plane and beam-hole discontinuities for the analysis, but reported only for the serpentine folded-waveguide slow-wave structure. The cold test measurement technique was reported only for the dispersion characteristics. Hence the measurement technique has to be extended for the measurement of interaction impedance.
The author proposes to orient the present doctoral work to (i) extend the proposed cascaded transmission matrix equivalent model for the analysis of rectangular folded-waveguide slow-wave structure, (ii) develop a non-resonant perturbation technique for the measurement of interaction impedance characteristics of the folded-waveguide slow-wave structure and also to (iii) establish new analysis models for the folded-waveguide slow-wave structure. The effect of E-plane bend and beam-hole discontinuities on the RF characteristics have been considered and simple, yet accurate closed form expressions for the computation of dispersion and interaction impedance characteristics have been established by three different approaches namely: transmission line equivalent circuit model, conformal mapping equivalent circuit model and quasi-TEM approach. The analysis results are benchmarked against 3-D electromagnetic modeling. The non-resonant perturbation theory is developed for the interaction impedance measurement. Typical Ka-band structures are fabricated by wire-EDM process and cold test measurements are carried out to benchmark the analysis approaches.
The equivalent circuit models based on lumped circuit model are simpler than the cascaded matrix equivalent circuit model and can give closed form expressions for the prediction of dispersion and interaction impedance characteristics. The quasi-TEM approach can be extended for the complicated structure like ridge-loaded FWG-SWS.
Broad-banding of the conventional folded-waveguide slow-wave structure is attempted by ridge-loading on the broad wall of the structure. The ridge-loaded folded-waveguide slow-wave structure is analyzed by parametric approach, cascaded transmission matrix equivalent circuit model and quasi-TEM approach and validated against numerical simulation. The analysis is extended for exploring the efficacy of the ridge-loading on broad-banding of the traveling-wave tube.
Finally efficiency enhancement of the folded-waveguide slow-wave structure is attempted by introducing grating on the broad wall of the structure. The analysis is carried out by numerical simulation for exploring the efficacy of the grating on efficiency enhancement of the traveling-wave tube.
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Sumathy, M. "Analysis Of Broad-band And High-Efficiency Folded-Waveguide Slow-Wave Structure For Millimeter-Wave Traveling-Wave Tubes." Thesis, 2011. http://hdl.handle.net/2005/2372.
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Vacuum microwave tubes, such as klystron, traveling-wave tube, gyrotron are high efficiency devices, where the RF interaction structure facilitates efficient energy transfer from the kinetic energy of the high energy electron beam to the electromagnetic wave. Traveling-wave Tube is the most versatile microwave power amplifier widely used for terrestrial communication, radar and aerospace applications.
The waveguide based slow-wave structures like Millman, Karp, inter digital, grated waveguide, ring-plane, ring-bar, millitron and folded-waveguide structure gathered importance for application in millimeter-wave traveling-wave tubes. Among these millimeter-wave interaction structures, the folded-waveguide slow-wave structure became the most popular due to its robust structure, high power capability, low RF loss, simpler coupling, reasonably wide bandwidth and ease of fabrication for millimeter-wave to terahertz frequencies. Hence this thesis aims to analyse the folded-waveguide slow-wave structure for broad-banding and efficiency enhancement.
The existing approaches for the analysis of cold circuit parameters (dispersion and interaction impedance characteristics) of folded-waveguide slow-wave structure are reinvestigated and found that these have limitation, as the effects of E-plane bend and beam-hole discontinuities are ignored in the parametric analysis. A cascaded matrix equivalent circuit model includes the effect of E-plane and beam-hole discontinuities for the analysis, but reported only for the serpentine folded-waveguide slow-wave structure. The cold test measurement technique was reported only for the dispersion characteristics. Hence the measurement technique has to be extended for the measurement of interaction impedance.
The author proposes to orient the present doctoral work to (i) extend the proposed cascaded transmission matrix equivalent model for the analysis of rectangular folded-waveguide slow-wave structure, (ii) develop a non-resonant perturbation technique for the measurement of interaction impedance characteristics of the folded-waveguide slow-wave structure and also to (iii) establish new analysis models for the folded-waveguide slow-wave structure. The effect of E-plane bend and beam-hole discontinuities on the RF characteristics have been considered and simple, yet accurate closed form expressions for the computation of dispersion and interaction impedance characteristics have been established by three different approaches namely: transmission line equivalent circuit model, conformal mapping equivalent circuit model and quasi-TEM approach. The analysis results are benchmarked against 3-D electromagnetic modeling. The non-resonant perturbation theory is developed for the interaction impedance measurement. Typical Ka-band structures are fabricated by wire-EDM process and cold test measurements are carried out to benchmark the analysis approaches.
The equivalent circuit models based on lumped circuit model are simpler than the cascaded matrix equivalent circuit model and can give closed form expressions for the prediction of dispersion and interaction impedance characteristics. The quasi-TEM approach can be extended for the complicated structure like ridge-loaded FWG-SWS.
Broad-banding of the conventional folded-waveguide slow-wave structure is attempted by ridge-loading on the broad wall of the structure. The ridge-loaded folded-waveguide slow-wave structure is analyzed by parametric approach, cascaded transmission matrix equivalent circuit model and quasi-TEM approach and validated against numerical simulation. The analysis is extended for exploring the efficacy of the ridge-loading on broad-banding of the traveling-wave tube.
Finally efficiency enhancement of the folded-waveguide slow-wave structure is attempted by introducing grating on the broad wall of the structure. The analysis is carried out by numerical simulation for exploring the efficacy of the grating on efficiency enhancement of the traveling-wave tube.
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Christie, V. Latha. "Analysis Of Coupled-Resonator Slow-Wave Structures For Traveling-Wave Tubes For Aerospace Applications." Thesis, 2007. https://etd.iisc.ac.in/handle/2005/478.
Full textAbstract:
Through continued innovation and growth, traveling wave tube amplifiers (TWTAs) remains the microwave power amplifiers of choice in a wide range of high power microwave and millimeter-wave applications specifically for aerospace applications with the volume, weight, bandwidth and power constraints. These advances can be credited to device innovation, improved modeling and design and development of advanced materials and construction techniques. This thesis aims at advancing the present technology of TWTs with coupled resonator slow-wave structures (SWSs) by a combination of device innovation, development of enhanced analytical and field analysis codes and understanding gained through improved modeling, simulation and experimentation. In a TWT, the SWS that slows the RF wave velocity down to near the electron beam velocity for interaction with the electron beam primarily determines the microwave performances of the tube. As compared to helix SWS, the coupled resonator SWS is capable of handling high peak and average powers with higher efficiency and TWTs based on these SWS are well suited for air-borne or space-borne radar systems and the major focus of this thesis is on the analysis and design of coupled resonator SWSs.
As a part of this thesis, improved analytical codes based on quasi-TEM analysis and equivalent circuit analysis have been developed. The technical formulation is explained and the improvements made for enhanced accuracy and for incorporation of different types of coupled resonator SWSs detailed. Using these models new variants of coupled resonator SWSs have been investigated. The SWSs proposed are the ladder-core inverted slot mode SWS and the inductively loaded inter digital SWS (ILID-SWS). The possibility of achieving both coalesced mode design that gives wide bandwidth and multi beam design that improves the peak power and gain using rectangular ILID-SWS is presented. The properties of these proposed SWSs have been compared with the existing SWSs and found to give superior performance. Also an improved modeling and simulation technique using 3-D electromagnetic codes has been proposed and the conventional cold test measurement procedure has been modified for more accurate results. Numerous illustrative examples are presented throughout the thesis highlighting the analytical model and simulation code validation with experimental results. The experimentations have been carried out on the real SWS model that have been fabricated and assembled.
Further, the contribution of the thesis is towards the development of a field analysis model for analysis of a corrugated waveguide SWS, based on the coupled integral equation technique (CIET), which is a combination of mode matching technique (MMT) and method of moments. The technical formulation and computational methodology employed in the model are explained and some of the most important aspects of implementation like the handling of singularities and choice of parameters controlling the accuracy is discussed. The accuracy and speed of the code is demonstrated by comparing CIET with MMT and 3-D electro magnetic simulators based on finite difference time domain (FDTD) method and finite element method (FEM). The CIET code developed is quite faster than the existing numerical methods and helps in solving the convergence problem associated with the MMT.
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Christie, V. Latha. "Analysis Of Coupled-Resonator Slow-Wave Structures For Traveling-Wave Tubes For Aerospace Applications." Thesis, 2007. http://hdl.handle.net/2005/478.
Full textAbstract:
Through continued innovation and growth, traveling wave tube amplifiers (TWTAs) remains the microwave power amplifiers of choice in a wide range of high power microwave and millimeter-wave applications specifically for aerospace applications with the volume, weight, bandwidth and power constraints. These advances can be credited to device innovation, improved modeling and design and development of advanced materials and construction techniques. This thesis aims at advancing the present technology of TWTs with coupled resonator slow-wave structures (SWSs) by a combination of device innovation, development of enhanced analytical and field analysis codes and understanding gained through improved modeling, simulation and experimentation. In a TWT, the SWS that slows the RF wave velocity down to near the electron beam velocity for interaction with the electron beam primarily determines the microwave performances of the tube. As compared to helix SWS, the coupled resonator SWS is capable of handling high peak and average powers with higher efficiency and TWTs based on these SWS are well suited for air-borne or space-borne radar systems and the major focus of this thesis is on the analysis and design of coupled resonator SWSs.
As a part of this thesis, improved analytical codes based on quasi-TEM analysis and equivalent circuit analysis have been developed. The technical formulation is explained and the improvements made for enhanced accuracy and for incorporation of different types of coupled resonator SWSs detailed. Using these models new variants of coupled resonator SWSs have been investigated. The SWSs proposed are the ladder-core inverted slot mode SWS and the inductively loaded inter digital SWS (ILID-SWS). The possibility of achieving both coalesced mode design that gives wide bandwidth and multi beam design that improves the peak power and gain using rectangular ILID-SWS is presented. The properties of these proposed SWSs have been compared with the existing SWSs and found to give superior performance. Also an improved modeling and simulation technique using 3-D electromagnetic codes has been proposed and the conventional cold test measurement procedure has been modified for more accurate results. Numerous illustrative examples are presented throughout the thesis highlighting the analytical model and simulation code validation with experimental results. The experimentations have been carried out on the real SWS model that have been fabricated and assembled.
Further, the contribution of the thesis is towards the development of a field analysis model for analysis of a corrugated waveguide SWS, based on the coupled integral equation technique (CIET), which is a combination of mode matching technique (MMT) and method of moments. The technical formulation and computational methodology employed in the model are explained and some of the most important aspects of implementation like the handling of singularities and choice of parameters controlling the accuracy is discussed. The accuracy and speed of the code is demonstrated by comparing CIET with MMT and 3-D electro magnetic simulators based on finite difference time domain (FDTD) method and finite element method (FEM). The CIET code developed is quite faster than the existing numerical methods and helps in solving the convergence problem associated with the MMT.
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Converse, Mark. "Investigation of the mechanisms of pulse amplification in helical traveling wave tubes." 2003. http://www.library.wisc.edu/databases/connect/dissertations.html.
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Wohlbier, John G. "Modeling and analysis of a traveling wave tube under multitone excitation." 2000. http://catalog.hathitrust.org/api/volumes/oclc/46320610.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 2000.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (p. 84-87).
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Wirth, Michael. "Experimental investigations of a custom-made, helical traveling wave tube amplifier." 2002. http://catalog.hathitrust.org/api/volumes/oclc/50178953.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 2002.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 43).
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Yan, Ying-Chu, and 顏英竹. "Theoretical Study of Ultra-High Power Gyrotron Traveling-Wave Tube Amplifier." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/52224154603808784786.
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Hsu, Ming Shyang, and 許明祥. "Implementation of High Voltage Power Supply Applied to the Traveling Wave Tube." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/94452542343522285244.
Full textAbstract:
碩士輔仁大學
電子工程學系
92
A high voltage power supply applied to the traveling wave tube (TWT) is proposed in this paper. A Buck current-fed full bridge converter is used to reduce the effect of leakage inductances of high voltage transformer for improving the performance. The switching frequency of the converter is chosen at 100 kHz to reduce the size and weight of power supply. The transformer windings utilize 19 kV insulation wire. The high voltage output rectifier and double voltage multiplier provided the need for multiple high voltage outputs for cathode, collector-1, collector-2 of the TWT, respectively. This paper mentioned the simply scheme to develop and design the high voltage power supply. Finally, computer simulation and experimental results of laboratory prototype with 100 kHz、10 kV and 1 kW output are presented to demonstrate the feasibility of circuit topology.
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Gallagher, Sean M. "Techniques in microfabrication of a 400 GHz folded waveguide traveling wave tube." 2003. http://catalog.hathitrust.org/api/volumes/oclc/51766534.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 2003.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 125-127).
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謝明泰. "Design of a High Voltage Power Supply for Traveling Wave Tube Using Feedforward Compensation." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/02437527780604889816.
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Badke, Bradley Paul. "A computer implementation of a mathematical model of an O-type traveling wave tube amplifier." 1988. http://hdl.handle.net/2097/23727.
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Chiu, Chen Chi, and 邱陳琦. "Theoretic Investigation of Gyrotron Traveling Wave Tube Amplifier with High Power and Broad-Band Capabilities." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/73305341925499414093.
Full textAbstract:
博士國立清華大學
物理學系
95
High power and broad-band gyrotron traveling wave tube amplifier (gyro-TWT) was required for advanced radar applications, remote sensing, imaging, and space object identification in 92-94 GHz atmospheric window. As is well known, the operation of gyro-TWT was largely restricted by absolute instability which is a more serious problem to gyro-TWT than to conventional TWT, since gyro-TWT usually operates near the cut off frequency of the waveguide. Beginning from the study of various absolute instabilities in a high-order, TE01 mode, distributed-loss gyro-TWT, a systematic optimization of the performance was then proposed under the zero-drive stable condition. This device is recently designed and currently in operation at UC Davis, which can be taken as an illustration of a guide to achieve high power and broad bandwidth. The optimization processes addressed here can be applied to other gyro-TWT design as well. The development of W-band TE01 mode gyro-TWT is collaboration between NTHU and UC Davis groups. The experimental works are conducted in the United States, while the simulation works are supported by NTHU in Taiwan. The current status on the UC Davis experiments and the corresponding simulation works are reported.
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Chuang, Ching-Fang, and 莊景芳. "Application of High Voltage and High Frequency Power Supply for the Traveling Wave Tube Circuit System." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/82473277714267789922.
Full textAbstract:
碩士輔仁大學
電子工程學系
89
ABSTRACT The traveling wave tube is a device that can change the RF signal strength and frequency modification by input control signal. It is widely used in the list of electric application strategies as below: Doppler radar system, electronic counter-measurement system, guide missile system, the satellite communication system, television translating system, the low noise amplifier receiver, high band radar system, the wave source of dot matrix in phase, …and so on. The merit is it only needs the stable input power equipment with the guarantee to work fine. Again, because of the different operating frequency and output power in different working place, the current solutions can’t meet its need. The contribution of this thesis is the buck current-fed full bridge power converter because the better adapting. It is in designing and manufacture of the topology. It is approved by the quality and reliability.
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Shiao, Jhih-Liang, and 蕭誌良. "A Study of Operating Regimes of a Gyrotron Traveling-Wave Tube Driven by an External Signal." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/21810689703265754785.
Full textAbstract:
碩士南台科技大學
光電工程系
97
A gyrotron backward wave oscillator and traveling wave tube are a promising source of coherent millimeter wave radiation based on the electron maser instability. However, the requirement on phase coherence is strict for applications. In the gyro-BWO, oscillations build up via the ECM interaction in an internal feedback loop composed of the forward moving electron beam and backward propagation waves. Using a nonlinear self-consistent time-independent code to simulated gyro-BWO driven by an external signal and analyze of efficiency as function of drive power, efficiency and gain as function of difference current and comparison with the measured results of NTHU. In this paper, using distributed-loss Gyro-TWA and operating at different current, the simulation results of gyro-TWA driven by an external signal show that there are three roots exist. And only need very small injection of power to achieve stable phase-locking oscillation and with high output power and high-gain. When the beam current is below free-running start oscillation current, the results of the nonlinear simulation are consistent with the results of the amplifier’s linear theory. This is an amplifier regime. When the beam current is above start oscillation current, there are three different operating regimes, amplifier regime, mode competing regime and phase-locking oscillation regime in a gyro-TWA driven by an external signal. There are three possible regime, amplifier regime, unstable regime and phase-locking oscillation regime in the mode competing regime. Using steady-state solution and locking bandwidth curve to analyze Gyro-TWA operation in phase-locking oscillation regime. Performance of gyro-TWA is predicted to yield the peak power of 200 kW corresponds to a saturated gain of 90 dB and saturated efficiency of 27%, bandwidth of 7 GHz and electron beam with an axial velocity spread 5 %. In the mode competing, when the traveling wave tube operating in the phase-locking oscillation mode can effectively suppress the oscillation of non-operating mode. Using this mechanism in low-voltage operation of the Gyro-TWA, will have high current and intention length of long, so can compensate for low operating voltage drop caused by the efficiency of decrease.
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Chang, Shun-Chiao, and 張舜喬. "Theoretical Investigation of Harmonic Gyrotron Traveling Wave Tube Amplifier with High Efficiency, Power, Gain, and Broadband Capabilities." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/93298456062534524967.
Full textAbstract:
碩士國立臺灣大學
物理研究所
100
High power and broad-band gyrotron traveling wave tube amplifier (gyro-TWT) is employed in satellite communication and millimeter-wave radar which provides higher resolution and penetrates deeper under foggy and smoky conditions in Ka-band that covers the frequency of 26.5-40 GHz. As is well known, the efficiency so as to power capability of gyro-TWT in second harmonic operation was significantly restricted by harmonic cyclotron interaction strength and inherent nonlinear effect. Beginning from the study of convective instability, TE11 mode, distributed-loss gyro-TWT which features the ultra-high gain and broad-band operation, the high efficiency as well as high power second harmonic gyro-TWT could be achieved by enhancement of harmonic cyclotron interaction. The simulation work indicate that the method profoundly strengthen the performance of saturated efficiency as well as saturated power for second harmonic gyro-TWT. The results provide a remedy of efficiency for second harmonic operation which favors less magnetic-field requirement.