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.