"Experimental results on a high power CW klystron with an extended interaction catcher"

A klystron with a multi-cavity buncher and extended interaction catcher has been built and tested. The tube has external cavities which can be modified and adjusted quite easily. The frequency is around 900 MC., the power level 10.20 KW. CW. A three cavity buncher is followed by a slot coupled cavity slow wave structure using short slots and up to six cavities, with a Single output terminal. This is fundamentally a backward wave circuit designed to work near beam synchronism at and near the upper cut-off point of the first forward wave space harmonic. Results indicate how much improvement in efficiency-bandwidth product can be obtained with such a catcher before the limit due to self-oscillation is reached. Some results are also given for a different arrangement in which three of the six slot-coupled cavities are used as the final stage of the buncher and the other three as the catcher.