Helix Slow-wave Structure with Changed Pitches for a Q-band Traveling-wave Tube

In this paper, a helix slow-wave structure (SWS) with changed pitches for a Q-band traveling-wave tube (TWT) is proposed. Changed pitches are used to achieve more sufficient beam-wave interaction in the SWS. The high frequency characteristics and beam-wave interaction of the Q-band TWT are analyzed by using CST. The voltage standing wave ratio is less than 1.5 from 39 to 42 GHz. The simulation results of the beam-wave interaction show that the Q-band TWT with the changed pitches can generate output power of more than 80 W and electronic efficiency of 14% in the operating frequency band. The electronic efficiency reaches the maximum of 16.09% at 39 GHz.