Design, Beam-Wave Interaction, and Efficiency Enhancement Studies of Millimeter Wave Gyro-TWT With a Three-Stage Depressed Collector

In this article, a W-band gyrotron traveling wave tube (gyro-TWT) amplifier that uses periodically dielectric-loaded (PDL) waveguide and operates in TE01 mode is designed and studied for its stability against backward wave oscillations and beam wave interaction behavior. The subassemblies including a magnetron injection gun using E-GUN code, RF output window, and electron collector using “MAGIC 3-D” are investigated. The present particle-in-cell (PIC) simulation of millimeter-wave gyroTWT results in a peak RF power~195 kW in TE01 mode with an electronic efficiency of ~28% and a saturated gain of ~63 dB. Further, the overall efficiency of the device is enhanced by using a three-stage depressed collector, which is designed and simulated using “MAGIC 3-D.” The collection efficiency of the present collector is calculated as ~74% and the overall efficiency of the gyro-TWT is improved to ~60%.