Along with gyrotrons, IAP has proposed and brought to a high engineering level the amplifying variety of gyrodevices: gyroklystrons and gyro-TWTs. In their operation concept, gyroklystrons are analogous to conventional klystrons with straight beams. In the gyroklystron, energies of electrons of the helical wave beam are modulated in the input cavity under the action of an external signal, grouped in azimuthal bunches in the drift space, which is free of the microwave field, and then these bunches excite the output cavity. High-power gyroklystrons developed at IAP by I. I. Antakov,
E. V. Sokolov, E. V. Zasypkin, I. G. Gachev ensure a pulsed output power of 0.7 MW at a frequency
of 35 GHz and up to 0.4 MW at 95 GHz for a gain up to 30 dB and an electron efficiency of up to 30% within a band of up to 0.5%.