Journal of Theoretical and Applied Physics (JTAP) Nonlinear study of injection process types into the traveling wave tube with hollow electron beam Volume 13, 2019 Issue 2, May and June 2019 2023 11 17 Nonlinear study of injection process types into the traveling wave tube with hollow electron beam 10.1007/s40094-019-0327-2 EN Journal Article 2023 11 17 AbstractIn this paper, examples of all types of signal injection such as different signal , harmonic signal and multiple signal injections in a TWT including hollow electron beam near frequency 1800 MHz and within input powers lower than TWT saturation power has been analyzed using approximate analytical solution of S-MUSE model. Later, the results obtained from approximate analytical solution with large signal code LATTE, that is a Lagrangian model, have been tested and simulated so that the effect of input phase difference between drive and injected wave and the effect of input powers on the amplification value of drive and generated second-order harmonic waves were investigated. The phase difference between drive and harmonic waves is a key parameter in harmonic injection for increasing the output power of drive and second-order harmonic frequencies.