Accurate and Fast Thermal Analysis of Multistage Depressed Collectors for Traveling-Wave Tubes Using Finite-Element Method

This article presents an accurate and fast thermal analysis method for multistage depressed collectors (MDCs) of traveling-wave tubes using the finite-element method (FEM). In this method, a novel approach named an advanced multigrid nonlinear solver is proposed to significantly reduce the computing cost of thermal analysis of MDCs. Based on this method, a 3-D thermal design tool for MDCs called a thermal simulator (TS) is developed. By modeling the thermal behavior of various MDCs, the TS is validated, and it is found that the TS is much more efficient than the widely used commercial FEM codes, i.e., ANSYS and CST MPS. Moreover, the TS is accurately and seamlessly coupled with our previously developed electron trajectory code. Consequently, by utilizing the TS, the automated electrical-thermal cosimulation of MDCs is realized accurately and efficiently, which would be very useful for the design of high-performance MDCs.