Cosimulation and Cold Test Verification of a 220-GHz Sheet Beam Traveling-Wave Tube Amplifier

The design and cold test verification for a 220-GHz sheet beam traveling-wave tube (SB-TWT) are presented in this article. Although there are numerous studies regarding the design and simulation of SB-TWTs, most of them focus on the research of one or several component(s) of the SB-TWT. And, the beam-wave interaction simulations are generally based on ideal situations, for example, an ideal electron beam and an ideal focusing magnetic field. In order to improve the accuracy of the simulation predictions, two measures have been implemented in this study: 1) the beam-wave interaction cosimulation of the entire tube is carried out, in which the sheet electron beam generated by the electron gun (E-Gun) and the focusing magnetic field produced by the periodically cusped magnetic focusing structure are employed and 2) the remodeled high-frequency system based on the cold-cavity test results is used for the beam-wave interaction simulation. In addition, the high-frequency system's microfabrication and cold test are also presented. Measured S-parameters of the high-frequency system showed a 3-dB transmission bandwidth of 35.3 GHz (222.5-257.8 GHz). The beam-wave interaction cosimulation, employing the aforementioned measures, predicted an output power exceeding 85.8 W within a bandwidth of 20 GHz (220-240 GHz), accompanied by a corresponding gain of ≥22.45 dB.