Caracterização de estruturas de ondas lentas helicoidais para utilização em TWT de potência

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Author(s):	Daniel Teixeira Lopes Total Authors: 1
Document type:	Master's Dissertation
Press:	São Paulo.
Institution:	Universidade de São Paulo (USP). Instituto de Pesquisas Energéticas e Nucleares (IPEN/BT)
Defense date:	2007-10-19
Examining board members:	Claudio Costa Motta; Alberto José de Faro Orlando; Jiro Takahashi
Advisor:	Claudio Costa Motta
Abstract
In this work, a mathematical model and a measurement apparatus for aiding in the project and characterization of slow-wave structures for highpower traveling-wave tubes were developed. The objective is to obtain the phase velocity and the interaction impedance characteristics of a given slow-wave structure. A ring-bar slow-wave structure was mathematically modeled as a contrawound helix in a such way that several published and still unpublished results could be achieved. A microwave measurement apparatus was developed for the experimental characterization of the slow-wave structure under analysis. The measurement procedures are presented and the experimental results are compared to the theoretical predictions. The experimental results presented good reproducibility and differed from the theoretical ones in an expected way. It was considered that the mathematical model and the measurement apparatus, as well experimental procedures, already constitute a very important tool, which will have fundamental role in the design and manufacture of traveling-wave tubes. (AU)