Linearity of the Transverse Field Interaction in a Traveling Wave Tube

Using a specially modified version of the CHRISTINE 3D large signal TWT simulation code, we have compared the spent beam distributions and linearity properties of a transverse TWT with those of a comparable conventional tube. The large signal simulations include the effects of a finite beam size, which is allowed to vary self-consistently as the beam propagates along the interaction space. The DC beam power was constrained to be the same (646 W) in both designs, and each was separately optimized for maximum output power by choosing the optimum values of beam voltage and RF drive power. Both designs used the same values of the respective beam-wave interaction impedance. The computed spent beam distributions and the C3IM intermodulation levels were then compared