Influence of 2nd harmonic injection on the 1st harmonic extracted power in a traveling wave tube

Power saturation in travelling wave tubes (TWT's), induced by the nonlinearity of electron wave interaction, severely limits the efficiency, and distorts amplified signals. One of the main causes of saturation in TWT's is the " inertial saturation", resulting from the bunching of electrons subjected to a sinusoidal field. In this paper study of this bunching is given by developing a model of an electron beam subjected to a bi-harmonic field, (containing both 1st and 2nd harmonics) in the low gain regime. Then work with a simulation code is performed to study the role of second harmonic injection in a TWT in the high gain, large signal regime and their results are given.