The AMOS (azimuthal mode simulator) code

AMOS, a newly developed computer code that is finding application in the design of accelerator cavities, is described. The program simulates the temporal evolution of electromagnetic fields in rotationally symmetric structures. An explicit Fourier series expansion is assumed in the azimuthal coordinate, which allows different multiple modes to be simulated independently. Nonuniform electrical properties (ε, μ, σ) are permitted, and both impedance and radiation boundary conditions are available. A geometric editor (DRAGON) allows for simple and rapid development/modification of models, and a direct CAD (computer-aided design) system-DRAGON data link is being used to facilitate the study of existing and developmental linac accelerator cells. A wakefield postprocessor (ANDY) allows the calculation of wake potentials, cavity impedances, etc. from AMOS simulation data. Code verification has consisted of comparisons with exact and approximate analytical results for simple geometries