Theoretical investigation of a high efficiency and broadband sub-terahertz gyrotron

This study investigates the electron dynamics of gyrotron interaction in a tapered waveguide and proposes an interaction structure for a 0.2-THz TE₀₂ reflective gyrotron backward-wave oscillator (gyro-BWO). The design shows the advantages of high power, continuous and broadband frequency tuning, mode converter free, and inherently possesses mode-selective ability to suppress the potentially competing TE₂₂ mode. Calculated results indicate that the reflective TE₀₂ gyro-BWO is capable of generating a peak power of 3.3 kW corresponding to 26.3% interacting efficiency with a broad 3dB-tuning-bandwidth of 6.9 GHz at beam current I_b = 0.5 A and beam voltage V_b = 25 kV.