Oscillation-amplitude fluctuations of a BWT operating in the short-wave part of the millimeter range

An experimental study of radiation-amplitude fluctuations of a backward wave tube in the 0.15-2000 MHz range is presented. The intensity of fluctuations depends on the accelerating voltage V sub y; in the oscillation range, the intensity has a number of maxima and minima just like the slope of the amplitude-accelerating voltage curve. The spectral density of relative fluctuations S(alpha) was found to be practically constant at frequencies less than 200 MHz and to have values of (3-8) x 10 to the -17th/Hz in minima over V sub y. At the end of the frequency range investigated, minimal S(alpha) values decrease by 1.2-1.5 times while maximal S(alpha) values decrease by 5-6 times.