CHRISTINE: A Multifrequency Parametric Simulation Code for Traveling Wave Tube Amplifiers.

Abstract : A model and computer code are presented that simulate the operation of traveling wave tube amplifiers (TWTs). The model is based on the well known parametric theory in which the relevant properties of the interaction circuit are the phase velocity and coupling impedance of the waves supported by the slow wave structure. The model includes a multifrequency description of both the fields of the structure and the space charge fields. This allows for the study of harmonic and intermodulation distortion. The beam is treated as an ensemble of disks with an effective axial velocity spread. Several options are available for specifying the parameters of the interaction circuit: using a sheath helix description, importing data from another model, or using data from experimental measurement. The advantages of the code are that it can relatively quickly simulate situations in which the amplifier is driven by multiple input frequencies, it is readily portable to different platforms, and it facilitates tube design by enabling users to vary parameters relatively easily.