A simplified method for calculating klystron performance

Power Klystrons and Related Devices

“…Here a high-velocity electron beam is successively passed through an input cavity resonator called the " buncher," then a field-free " drift space," followed by an output cavity resonator, and finally the beam proceeds to a "collector" electrode. This analysis is best handled by means of a computer program, and has also been extended to the case of three or more cavities in cascade [11,12]. Depending on whether an electron in question encounters a positive or a negative field at this gap, it will be either accelerated or slowed down.…”

“…1 rarely gives a power gain of more than 10 dB, or efficiencies in excess of 25-30%. The reason for the increase in efficiency is not immediately clear, but this has been extensively investigated theoretically and shown to be related to improvement in bunch density arising from suitably spaced intermediate cavities [10][11][12]. Gain figures in excess of 35 dB and 30 MW of output were demonstrated by Chodorow et al as early as 1953 in an S-band tube with three cavities [4], and in 1961, Clough et ai demonstrated efficiencies above 60 % in a four-cavity tube with a gain of 30 dB at 400 Mc and 15 MW [13].…”

“…In general, theoretical treatment [10][11][12] has derived the fundamental component of the output gap current bunch. This is then translated into an equivalent current generator supplying power to the resonant impedance of the output cavity.…”