Comparison of different methods of suppression of self-excitation broadband twt on a backward wave in view of a beam expansion at the expense of a dynamic defocusing

The comparative efficiency of different methods of TWT self-excitation suppression on a backward wave in a dynamic mode is investigated in view of expansion of a beam. The suppression of oscillation on a backward wave by spring of a step of a slow-wave structure (SWS) in devices with a normal dispersion (ND) along the whole length, by jump of a step and slope of a dispersion in devices with an abnormal dispersion (AD) in output section, and also by a jump of a drift channel diameter and a jump of a phase in both types of devices is explored. It is shown, how many a start current of self- excitation on a backward wave varies at usage in them of different methods of its suppression in these devices.