NDLI: Accurate 3-D simulation of coupled-cavity TWT structures

Content Provider	IEEE Xplore Digital Library
Author	Cooke, S.J. Levush, B.
Copyright Year	2004
Description	Author affiliation: Vacuum Electron. Branch, Washington, DC, USA (Cooke, S.J.; Levush, B.)
Abstract	Summary form only given. We describe a new 3D electromagnetic simulation code capable of fast, accurate modeling of both resonant cavities and slow-wave structures. We also present results of a new method to obtain complete dispersion properties for a 3D coupled-cavity TWT structure based on analysis of only the computed /spl pi/- and 2/spl pi/-modes. The underlying electromagnetic algorithm uses the finite element method on an unstructured conformal mesh, with both quadratic elements and quadratic basis functions to rapidly achieve a high degree of accuracy. For example, the /spl pi/-mode frequency of a coupled-cavity: TWT can be determined to 0.1% accuracy in 2-3 minutes on a 2 GHz PC. To determine dispersion curves for a coupled-cavity TWT, we model a chain of cavities using an open-mode expansion method. Fields in each cavity are represented as a linear combination of a small set of precomputed /spl pi/- and 2/spl pi/-eigenmode fields of the cavity, so that just a few mode amplitudes represent the complete 3D field. Coupling between adjacent cavities is calculated using a set of integrals over the cavity interfaces, derived directly from Maxwell's equations. This formulation allows us to obtain a small matrix representation for the complete system that may be solved directly, for either the discrete modes of a chain of cavities or by applying a Floquet boundary condition to reduced representation of a single cavity. Results of this method are compared to experimental data. The core code has been written in object-oriented C++ for high performance, but most of the functionality is made directly available from within the Python language. This provides a simple yet highly flexible interface for specifying problem data, such as boundary conditions or material properties, or for automating complex calculations. At present, the mesh is imported from a commercial mesh generation tool, supporting a CAD interface, though a variety of mesh file formats are supported.
Sponsorship	Plasma Sci. and Applications Committee of the IEEE Nuclear and Plasma Sci. Soc
File Size	73981
File Format	PDF
ISBN	0780383346
ISSN	07309244
DOI	10.1109/PLASMA.2004.1340015
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2004-07-01
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Object oriented modeling Boundary conditions Computational modeling Electromagnetic modeling Resonance Finite element methods Frequency Integral equations Maxwell equations Material properties
Content Type	Text
Resource Type	Article
Subject	Atomic and Molecular Physics, and Optics Condensed Matter Physics Electrical and Electronic Engineering

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