Development of RF windows for 650 MHz multibeam klystron

Radio frequency (RF) windows are developed and evaluated for a 650 MHz continuous-wave (CW) multibeam klystron. Thin-pillbox windows with alumina and beryllia disks are designed with an average RF power of CW 400 kW. Results of a cold test and tuning procedures are described. The final measured S11 curves under the required bandwidth are less than -32.0 and -26.9 dB for alumina and beryllia windows, respectively. The windows are tested up to CW 143 kW for traveling waves and CW 110 kW for standing waves using a solid-state amplifier as an RF power source. Multipactor simulations for windows and benchmark studies for the thermal analysis of ceramic disks are introduced.