Parametric oscillations in high-power injected beam crossed-field amplifiers and TWT´s

One class of spurious signals observed in high-power microwave amplifiers, called parametric oscillations, has not been accounted for by any conventional method of analysis. This paper proposes a model, based on empirical observations, which has been theoretically analyzed. It is shown that the occurence of parametric oscillations is coupled with the appearance of very-low-frequency oscillations (100 MHz). These low-frequency signals are directly related to the stopband of the slow-wave structure, have been observed experimentally in IBCFA, and may be responsible for the so-called"power-suckout" in TWT\´s and CFA\´s.