Two-harmonic prebunching of electrons in multicavity gyrodevices

The theory of multicavity gyrodevices has been developed for the case when two prebunching cavities may operate at different harmonics of cyclotron frequency. It is shown that when the first cavity operates at the fundamental and the second cavity at the second harmonic, the harmonic content in an electron beam current and the efficiency of operation in the third, output cavity are higher than these when two first cavities operate at the fundamental. The efficiency of operation of the output cavity at the first four cyclotron harmonics was studied with the account for electron velocity spread for both, single- and two-harmonic prebunching cases. The results obtained permit one to estimate the efficiency of operation of multicavity gyrodevices at cyclotron harmonics and its sensitivity to electron velocity spread.