The objective of this thesis is to consolidate previously reported results on numerical methods for attaining flat amplitude response in multi-cavity klystrons. The work done by Isaacs, Schrack, and Yuan at the University of British Columbia is extended so as to apply to a representation of the power-gain function based on Bers' theory of the interaction between an electric field and an electron beam. It is shown that an iterative numerical method can be used in designing for flat response, contrary to the conclusion drawn by McCullough on the basis of Bers' theory. That conclusion results from the failure to consider the frequency dependence of the transadmittances appearing in the power-gain function. It is shown that one of the two terms in the transadmittance is an odd function of frequency which can be approximated by a linear function. The other term is an even function of frequency which can be approximated by a constant. If these approximations are made for each transadmittance, the resulting power-gain function is even, a requirement which must be fulfilled for physical realizability as well as for the applicability of the iterative method. Yuan has previously shown that the optimum tuning pattern for a multi-cavity klystron can be determined by considering the numerator polynomial of the power-gain function. It is shown here that the variations, in the loaded Q's of the input and output cavities must also be considered. A modified method for selecting the optimum tuning pattern is presented. A numerical example is given which illustrates the application of the modified method, using the iterative procedure to determine the pole positions and power gain for each tuning pattern. The numerical data for this example was the same as that used by Blötekjaer at the Norwegian Defense Research Establishment in a similar study in which an analog device was used to determine the relative merit of the different tuning patterns for a klystron. It is shown that the predicted optimum tuning pattern does actually give the highest gain and that the results from the numerical and analog methods are essentially identical. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The drift length of a two-cavity klystron amplifier for highest power gain is one-quarter of the reduced space-charge wavelength λq. The presently accepted values for these optimum drift lengths for a multi-cavity klystron amplifier are also one-quarter of λq. These lengths are obtained from an extrapolation of the two-cavity klystron by regarding the multi-cavity klystron as a cascade amplifier consisting of several two-cavity stages. In this thesis, the multi-cavity klystron amplifier is considered as an entity, and not as a cascade amplifier. It is shown that if the power-gain function of a flat-staggered design is optimized with respect to the drift lengths, a set of unequal lengths is obtained. The optimization of the drift lengths leads to an appreciable increase in gain with a negligible increase in overall tube length. Hence it is worthwhile not to regard the multi-cavity klystron amplifier as a cascade amplifier. Only the small-signal theory is considered in this thesis. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

A field modulation, paramagnetic resonance spectrometer in use as a wide band Instrument employs a reflex klystron. The frequency of the klystron has been stabilized to at least one part in one quarter million, over a period of a few hours, to the resonant frequency of a microwave cavity. A variation of the A.C. Pound stabilizing circuit was employed. With field stabilization, this frequency stabilization makes it possible to operate the spectrometer as a narrow band instrument, thereby increasing the overall sensitivity. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 81-83.

No description available.

Experiments were carried out to determine the characteristics of a reflection-type modulator. The modulator consisted of an E-plane T-junction that was terminated on the side-arm by a reflex klystron operating in the passive region. Switching was accomplished by applying a pulse to the repeller of the passive klystron. It was found that the switching characteristics were strongly dependent on the power level at the input to the modulator. Good switching characteristics were obtained at low power levels hut these deteriorated as the input power became comparable to that produced by the klystron when operating as an oscillator. For the particular klystron used, satisfactory switching was possible for input power levels approximately 5 to 10 dB less than the output of the switching klystron. It was also found that the modulator characteristics depended on the operating mode of the passive klystron. The desired operating mode was a compromise between power-handling capability and the switching rate. An attempt was made to explain the decrease in switching range at high input power levels by relating the observed results to an increase in the bunching parameter at the boundaries of the passive region. However, this did not fully account for the observed results. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

J. Jensen. / "January 26, 1951." / Bibliography: p. 13. / Army Signal Corps Contract No. W36-039-sc-32037. Project No. 102B. Dept. of the Army Project No. 3-99-10-022.

Millimeter waves, corresponding to the frequency range 30 to 300 GHz, have characteristics which make them ideal for many applications. Antennas at these frequencies have the advantage of reduced size and weight and can be fabricated as an integral part of the system they are used in. Millimeter wave microstrip antennas have been extensively researched over the past decade. The purposed of this report was to build and test 35 GHz microstrip antennas as well as put into operation a high voltage klystron power supply, Micro-Now Model 756. The antennas were fabricated and tested in the lab and the results obtained are reported. The operation of the Model 756 power supply is also outlined in detail.

Cette thèse propose une méthodologie complète de conception des transformateurs utilisés dans les modulateurs servant à alimenter, par des impulsions de haute tension, des amplificateurs klystron. Cette méthodologie est appliquée au transformateur d'impulsion monolithique du modulateur qui doit fournir des impulsions de 28.9 MW pendant 140 µs, à une tension de -170 kV pour le futur accélérateur d'électrons-positrons CLIC actuellement en phase de recherche et développement à l'organisation européenne pour la recherche nucléaire (CERN). Une attention particulière est donnée au respect du temps de montée de la tension du klystron qui doit être inférieur à 3 µs, et à la tension maximale qui ne doit pas être inférieure à -175 kV. Les circuits électriques équivalents respectifs du transformateur, incluant capacités et inductances parasites, et du klystron permettent de modéliser le comportement électrique du modulateur. Un circuit équivalent défini dans le standard 390 de l'IEEE ainsi qu'un circuit équivalent d'ordre élevé sont utilisés. Il est possible par simulation des circuits équivalents de connaître le courant et la tension au secondaire du transformateur lorsque la tension au primaire est imposée. A partir des caractéristiques du transformateur et des matériaux le constituant, l'identification des éléments parasites à l'aide de calculs analytiques ou de simulations avec la méthode des éléments finis en 2D ou en 3D du transformateur est présentée. Une méthodologie d'identification expérimentale du circuit équivalent standard du transformateur est développée afin de comparer les méthodes d'identification par calcul et simulation avec des mesures réalisées sur un transformateur. Le système d'isolation est dimensionné à partir d'essais haute tension réalisés sur les matériaux solides et liquides. Les modèles de dimensionnement et d'isolation sont validés expérimentalement sur deux prototypes. Des résonances non modélisées avec le circuit équivalent standard et reproduites par le circuit équivalent d'ordre élevé sont observées expérimentalement sur les deux prototypes à échelle réduite. Le circuit équivalent standard et l'identification sont utilisés dans une procédure d'optimisation pour dimensionner un avant-projet de transformateur respectant le cahier des charges du CLIC. Un algorithme d'optimisation hybride utilisant conjointement des modèles de dimensionnement de basse et haute précision pour un résultat rapide et précis est présenté et détaillé. / In this thesis, a pulse transformer design methodology for klystron amplifiers is presented. This methodology is applied to the design of the pulse transformer for the modulator of a future electron-positron compact linear accelerator (CLIC) at CERN which has to produce -170 kV pulses of 140 µs duration with a power of 28.9 MW. A special care is given to the secondary voltage maximum value and rise time of respectively -175 kV and 3 µs. The electrical performances of the modulator are evaluated with equivalent circuits that include parasitic capacitances and inductances of the transformer, and nonlinear klystron resistance. The IEEE pulse transformer equivalent circuit and a high order generalized equivalent circuit are compared. From the transformer topology and its material characteristics, the elements of the equivalent circuits are identified with analytic computation (only for the standard equivalent circuit) or simulations of the electrical and magnetic fields of the transformer modeled in 2D or 3D using the finite elements method. Two reduced scale validation prototypes are realized. An experimental identification methodology of the standard equivalent circuit is developed to compare simulation and experimental results. The insulation structure is designed from high voltage tests on solid and liquid insulating materials and validated on prototypes. It is experimentally demonstrated that the high order generalized equivalent circuit predict the observed electrical resonances not predicted by the standard equivalent circuit. The standard equivalent circuit and its identification are used in an optimization procedure to design a pulse transformer that meets the specifications for the full scale CLIC modulators. The hybrid optimization algorithm (also called space mapping) that is associating analytic and 3D finite element simulations for a fast and precise solution is proposed and detailed.

Made available in DSpace on 2014-10-09T12:33:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:37Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP