A New Method for High Power Sheet Beam Traveling Wave Tube by Rotating the Beam Tunnel

The instability of the sheet electron beam (SEB) is an essential factor for limiting the power of the SEB traveling wave tube (TWT). To solve this issue, this article proposes a method to improve the output power of SEB TWTs, which introduces a rotating electron tunnel, following the SEB’s deflection instability, to significantly increase the input current and output power. In addition, the outer profile of the slow wave structure (SWS) is formed as a cylindrical to prevent this rotation from changing the high-frequency characteristics. To verify this method, a novel staggered double vane with a rotating tunnel (SDV-RT) SWS is proposed in this article. Moreover, a W-band TWT employing this new SWS is designed and simulated. The results illustrate that the beam current increases by approximately 57% under a uniform magnetic field of 0.85 T. Simulation results indicate that the designed SDV-RT TWT, operating with 1.1-A beam current and 27-kV beam voltage, achieves an output power over 2400 W, with a maximum power of 2759 W at 92 GHz. The output power is approximately 60% higher than that of conventional SDV devices under the same magnetic field. Additionally, an electron optical system (EOS) is designed to validate the effect of the RT method on enhancing output power under conditions of nonideal SEB and nonideal uniform magnetic fields. At last, the designed SWS has been fabricated, and the cold test results indicate that the S11 is below −16.5 dB and the S21 is above −2 dB in the frequency range of 90–100 GHz, showing good agreement with the simulation results.