Top part of the stand for testing of relativistic gyroklystrons with the following parameters of high-voltage pulses: 450 kV, 180 A, 1 μs, and a pulse repetition rate of up to 10 Hz. One can see components of the bioprotection system, the cryomagnet, and the microwave calorimeter

High-efficiency gyrodevices employing high-order volume modes, which operate at higher pulsed voltages as compared with conventional gyrodevices have been created at IAP (M. I. Petelin, N. I. Zaitsev, et al.). Such sources are promising for the use in new-generation amplifiers and radars. A power of 20 MW was obtained in the relativistic gyrotron with an efficiency of 50% at a frequency of 30 GHz with a pulse duration of 0.5 μs. Stable amplification and a high level of energy parameters are achieved in the relativistic gyroklystron by using high-order modes differing in radial indices in the input and output cavities. Specifically, an output power of 15 MW was achieved at an efficiency of 40%, a gain of 30 dB, and an amplification band of 50 MHz.