Electron bunching at the doubled frequency of the input wave and the use of this effect in klystron-type frequency multiplicators

A method of organizing electron-wave interaction at the doubled frequency of the signal wave is proposed. This type of electron-wave interaction provides doubled-frequency electron bunching, which means better bunching at the even harmonics of the input-signal frequency and, simultaneously, the absence of bunching at the odd harmonics. This effect is attractive for the use in the bunching sections of klystron-type cyclotron resonance masers with frequency multiplication as a way to increase the output frequency and to improve selectivity.