Development of a THz Broadband Mini-Gyrotron

We are currently investigating about demonstrating gyrotron with the capability of super broadband operation in THz band. A strong-field pulse magnet is applied to provide a time-varying magnetic field, and the cyclotron frequency of the electron beam in the cavity changes accordingly. The electron beam efficiently excites a backward wave in a specially designed pre-bunching cavity. A broadband quasioptical converter and a Brewster window are installed in the tube to radiate out the broadband power. Theoretical study reveals that the gyrotron is potential to radiate peak power about 1 kW around 0.33 THz and a frequency tuning range about 10 GHz in each pulse. Further study predicts that when high-order whispering gallery modes are employed as the operation modes, this broadband mini-gyrotron is capable of sequentially jumping from one mode to another and finally radiates power covering the range of 350 GHz - 410 GHz.