Design and Analysis of Overmoded RF Window for High-Power Applications in X-Band

This article presents the design and analysis of overmoded RF window for megawatt-class pulsed coaxial magnetron operating in X- band and other high-power systems such as linear accelerator (LINAC) and devices such as gyrotron and klystron. Three ingenious designs of RF windows are proposed based on the mode excitation techniques. Design 1 operates in TE012-type mode (mixed with TE113 and TE213), Design 2 in TE012-type mode (mixed with TE312), and Design 3 in TE014-type mode. Mixed-mode operation broadens the bandwidth of the RF window compared to single-mode operation. RF windows are simulated in CST and return losses are obtained as 55.04, 51.52, and 53.92 dB, and insertion losses as 0.054, 0.07, 0.194 dB, respectively. Return losses and insertion losses of the proposed designs are verified in HFSS, and results are in good agreement with the results obtained from CST. Coupled multiphysics analyses are carried out to study thermal and structural behaviors of the proposed RF windows. Sensitivity analysis of the windows is also performed to analyze the effect of mechanical deformation on the performance of S-parameters. Multipactor analysis is carried out to determine the safe operating power level, and multipactor thresholds are obtained as 10, 16, and 2.35 MW, respectively.