In a helix TWT (traveling wave tube) amplifier simulation, VSim captures the interaction of the electron beam with the helix coil RF signal. During device simulation, VSim can be used to optimize dispersion and attenuation, and tune the power output of a traveling wave tube. VSim provides subcell models for fields, as well as the particle sinks and sources. By creating separate simulations in VSim for the dispersion, attenuation, and power run, the designer can streamline the project