A new development of the monotron oscillator

A 2-cavity klystron has been built in which the first cavity acts as a monotron oscillator, while the second cavity and the drift tube provide amplification and a worth-while efficiency. The advantages of this system are a high frequency stability in the monotron cavity resulting from a high-Q-factor cavity and a large gap spacing. Furthermore, since the two cavities are coupled only by the beam, the frequency is independent of loading conditions. In many applications this will result in a single valve replacing an oscillator-amplifier combination. Existing theory of this type of operation can give only an indication of the starting current of a monotron, but is inadequate to determine the amplitude in the steady state. An X-band valve has been built giving a maximum output of 280 watts with an 8kV 165 mA beam. The amplitude in the monotron cavity is sufficient to modulate the beam fully, and the bunching efficiency is found to be comparable with that of a conventional klystron.