Design and Simulation Studies of a Continuously Tunable Sub-THz Gyrotron Using Magnetic and Thermal Tuning Schemes

In this article, the frequency tunability of a sub-Terahertz (THz) gyrotron has been investigated using both magnetic and thermal tuning schemes. A triode-type magnetron injection gun (MIG) has been designed using an electron optics tool, which predicted an annular electron beam with a < 4% velocity spread. Furthermore, the cavity has been modeled to operate in the TE11,2 mode at 527 GHz for dynamic nuclear polarization-nuclear magnetic resonance (DNP/NMR) applications. The transient behavior of the present gyrotron has been studied using a time-dependent self-consistent multimode code. A maximum continuous wave (CW) power of ~14 W was obtained at 527.20 GHz with 16.75 kV, 90 mA, and 1.85 pitch of e-beam. The tunable bandwidth has been obtained as ~0.31 GHz (527.20–527.51 GHz) by using a magnetic tuning scheme and ~0.31 GHz (526.90–527.20 GHz) by using the thermal tuning scheme by taking advantage of gyrotron sensitivity on cavity structural parameters and cavity shape.