Simulation of a depressed collector for millimeter wave gyrotron

Abstract

The trajectories of spent electron beam were simulated from the mode converter to the single-stage depressed collector for a W-band gyrotron. The spent beam trajectories and power distribution data obtained from large signal analysis were fed to the simulation model. The collector geometry and the magnetic field were profiled to ensure the landing of the electrons to the wider cylindrical section of the collector electrode for better thermal management, which was ensured with ±5% variation in the magnetic field and no electron interception. The power dissipation and the maximum thermal loading on the collector were 80.55 kW and 0.377 kW/cm2, respectively. The collector efficiency was ∼48% for 120 kW RF generation. The thermal analysis of the collector in pulsed condition with 10 and 40 L per minute flow rates predicted the maximum temperature at the collector electrode as 151.8°C and 133.3°C, respectively.