Development of Face-Cooled Tunable Double-Disk Sapphire Window for 42-GHz 200-kW Gyrotron

Window happens to be the most critical and vulnerable component in high-power gyrotrons. A face-cooled tunable double-disk sapphire window has been developed primarily for a 42-GHz 200-kW gyrotron. The critical issues like: sapphire-to-metal joining, electrical simulation, thermal analysis, structural analysis of the window, and its low-power characterizations in TE03 mode have been discussed. The return loss and insertion loss have been measured to be -29 and -0.12 dB, respectively. The window has been attached to the first Indian gyrotron and vacuum processed successfully.