The three-dimensional TWT multi-signal nonlinear beam-wave interaction

Based upon the model of Rowe's transmission-line equivalent circuit, using the maximal common submultiple fundamental frequency, a 3-dimensional (3D) multi-signal nonlinear model of beam-wave interaction in a helix traveling-wave tube (TWT) has been obtained. The 3D model describes 2D RF fields, 3D AC space-charge fields and 3D AC electron motion. This model has been implemented in the HTWT3D code, which can calculate any number of simultaneous signals, including input signals and their intermodulation components. Results from the HTWT3D code are shown to compare with measurements of output powers vs. driver power.