Stochastic phenomena in relativistic gyrodevices

We present a historical overview of stochastic phenomena in various relativistic gyrodevices. In stochastic process, the attention was focused on the analysis of temporal evolution of the electromagnetic (EM) field excited by an electron beam. It was shown that typically, as the beam current ratio to the start current increases, the EM field exhibits the series of transitions from stationary oscillations with the constant amplitude to the automodulation, and then to irregular oscillations, which can be treated as choatic ones and these oscillations were observed in gyro-BWO. In high power relativistic gyrodevices, the treatment was carried out assuming that the interaction between electrons and EM field takes place at an isolated fundamental cyclotron resonance exploiting weakly relativistic electron beams. We present the simulation corresponds to a second harmonic relativistic 30 GHz gyroklystron driven by a 500 kV electron beam and operating at the TE/sub 2,1/-mode at about 60 MW output power.