3D ARGUS-ESP computations of vacuum eigenmodes for standing-wave and traveling-wave structures

Summary form only given, as follows. The ARGUS-ESP code has been used to calculate electromagnetic vacuum eigenmodes, including dispersion diagrams, for both standing-wave and traveling-wave devices. Slow-wave structures, as used in microwave devices, are readily modeled with this code. ARGUS-ESP gives the designer the ability to do numerical cold testing. ARGUS is a fully 3D electromagnetic suite of codes that share a common framework. This common framework, across several methods of solution, gives ARGUS the ability to model complex structures in various ways. The suite includes electromagnetic eigenmode (ESP), time-domain, and single-frequency (or driven-frequency) models, as well as electrostatic models. Additionally, particle-in-cell (PIC) models are included in both time-domain and equilibrium (gun) modes. For this presentation, the ARGUS electromagnetic eigenmode solver, ESP, is featured. This solver gives the user the capability to calculate cavity modes for general, arbitrarily-complicated, structures. The eigenmode solver uses a fraction of the CPU time that a time-domain calculation would take, and yields a much higher accuracy of solution. In particular, this rapid frequency domain algorithm has incorporated in it a phase advance boundary condition that allows dispersion diagrams for devices to be readily determined, where only a single period of a structure needs to be gridded. Two examples of the application of this solver will be presented. The first example is a simulation of a helix TWT (including dielectric supports), showing how dispersion diagrams an attained. The second application models a 95 GHz coaxial magnetron tube, where the structure of slot modes as well as the basic operational mode shown.