1.7 kW power booster TWT at 35 GHz

Summary form only given. The development of a broadband multi-kW Ka-band PPM focused TWT driver-booster combination is reported. The driver is an existing broadband coupled-cavity TWT1, employing a 2 stage depressed collector. The power booster is a newly designed sever-less folded waveguide TWT designed to provide 3-4 dB of additional gain2. The booster also uses a 2 stage depressed collector and a slightly modified version of the same electron gun used in the driver. In order to accommodate the high power output of the booster over the full operating band, a new racetrack window was successfully designed built and tested. The maximum booster output power of ~ 1.75 kW at ~ 750 Watt CC-TWT input power at 35 GHz has been demonstrated. The booster output power of 1.5 kW over 5 GHz and of 1.25 kW over 7 GHz centered at 35 GHz has been measured. Beam current interception of ~ 7% has been observed in the power booster when operating > 1 kW, thus preventing a CW operation of the booster. The predictions from the 2.5D large signal TESLA-FW simulation code3 are in very good agreement with the measured data.