CTLSS - An advanced electromagnetic simulation tool for designing high-power microwave sources

Simulation-based-design (SBD) techniques to achieve "first-pass design succ ess" depend on the development of fast, accurate, realistic models that can handle material properties, geometry, and appropriate boundary conditions. This paper describes a new three-dimensional (3-D) electromagnetic and lar ge-signal simulation tool, Cold-Test and Large-Signal Simulator (CTLSS), wh ich has been developed as part of an SBD tool suite for vacuum electron dev ices. Computational electromagnetic codes are essential for applying the SBD meth odology to the design of vacuum electron devices and components. CTLSS offe rs the unique advantage that its computational electromagnetics model is li nked intimately with a large-signal simulation tool for computing the elect ron-wave interaction in the radiating structure. Currently, this link has b een implemented for helix traveling-wave tubes (TWT's) only, using the CHRI STINE code as the large-signal model, but a new, general, large-signal mode l is under development and is described in this paper. The electromagnetic simulation engine in CTLSS has been designed and implem ented as a volumetric frequency-domain model that can handle both resonant eigenvalue problems, using the Jacobi-Davidson algorithm, and nonresonant d riven-frequency problems, using the quasi-minimal residual (QMR) technique to invert the non-Hermitian matrices that often occur in real problems. The features and advantages of this code relative to other models and resul ts from the code for several classes of microwave devices are presented.