A Design Method for Interaction Circuit of High Efficiency Helix TWTs

In this paper, a design method for the interaction circuit of high efficiency helix traveling-wave tubes (TWTs) is presented. By observing the change of field relative phase, the method can quickly get a design scheme of the interaction circuit with phase-velocity tapering. The design steps are characterized in the paper, which has been revised by the engineering experience. The interaction circuit of a C-band helix TWT is designed by using this method, the output power and electronic efficiency are more than 120W and 25%, respectively.