Abstract:Background and Objectives: Many applications, such as highdata-rate wireless communications, spectroscopy, high-resolution radar, biomedical imaging, security, etc. require compact highpower sources of sub-THz radiation. Traveling wave tube (TWT) amplifiers are the most promising candidates for such sources combining 10-100 W power and wide b andwidth. Here we present the results of design and simulation of a 0.2 THz TWT with a grating slow-wave structure (SWS) and electron-optical system (EOS) with three elliptic-shaped beams. Materials and Methods: We have conducted numerical simulation of a 0.22 THz TWT amplifier with three elliptic-shaped electron beams and dual-grating staggered SWS. For SWS design and simulation of cold electromagnetic parameters, a fast and accurate code based on the integral equation method was used. For calculation of small-signal and large-signal gain regimes, the well-known 1D nonlinear frequency-domain TWT theory was used. Results: Dispersion characteristics of different transverse modes in the dual-grating SWS are calculated. The electron beam with 21.4 kV dc beam voltage is synchronous with the third-order transverse mode in a wide range of frequencies around 0.22 THz. Small-signal gain for 100 mA total beam current (i.e. 33.3 mA current of each beamlet) is calculated. For 21.4 kV beam voltage, the gain is around 15 dB in 200-250 GHz frequency band. Large signal gain calculations show that over 50 W output power may be attained. Conclusions: In this paper, the possibility of developing a 0.22 THz TWT amplifier with a dual-grating staggered SWS and electron beam consisting of three elliptic beamlets is considered. Such a design with increased cross section allows to decrease the current density, which opens up the possibility of a continuous-wave operation. In addition, it facilitates the beam focusing by the magnetic field.
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