Generation of dark envelope pulses in a modified noisetron scheme

The generation of dark envelope pulses with a duration of about $\sim$10 ns is obtained in a modified noisetron circuit consisting of two nonlinear amplifiers: a multicavity drift klystron and a travel-ing wave tube (TWT), captured by a delayed feedback circuit. The drift klystron operates in the output power saturation mode, and the TWT amplifier operates in the nonlinear cross mode, in which there are two $N$-shaped sections on the amplitude characteristic of the lamp, and the phase shift dependence on the signal power at the traveling wave tube entrance is highly nonlinear. It is shown that an increase in the chaotic signal power in a ring leads not only to a decrease in the average repetition period of dark envelope pulses, but also to the formation of bound states of dark and anti-dark envelope pulses.