An advanced electromagnetic eigenmode solver for vacuum electronics devices-CTLSS

Summary form only given. The first module of the Cold-Test and Large-Signal Simulation (CTLSS) code, a next generation design tool for vacuum electronics devices, is presented. The prototype tool is a three-dimensional, finite-difference, frequency-domain cold-test code that operates on a rectangular structured grid. It uses a generalisation of the Jacobi-Davidson algorithm that has proven effective in solving test problems having sharp-edged structures with materials having large dielectric constants and loss tangents as high as 100%. Cold-test codes typically have experienced difficulty handling moderate to large loss tangents in sharp-edged structures (i.e., problems in which there is a large gradient in the loss tangent across the numerical grid.) this talk will present the CTLSS cold-test algorithm and code features that are useful for vacuum electronics design. Analysis of both closed cavities and periodic slow-wave structures will be presented. Initial tests on closed cavities indicate that the CTLSS algorithm can determine normal-mode frequencies well below 0.1% accuracy for all modes computed. During the coming year this code will be generalised to include unstructured, finite-element numerical mesh for the conformal representation of structures. The cold-test fields will feed forward into a large-signal simulation model, based on the CHRISTINE code (Antonsen et al., 1997).