Recent developments on generalized large signal models for TWTs

We describe two large signal models of coupled-cavity traveling-wave tubes (CCTWTs) and folded-waveguide traveling-wave tubes (FWTWTs). These models include a generic theory derived from the Poynting's theorem and an equivalent circuit that uses a three-port network representation of the unit cell of the slow wave structures. Both of the models use the digital RF fields obtained from a 3-D finite element code, HFSS. The corresponding codes are applied to simulate the beam-wave interactions in a CCTWT and a FWTWT.