Preliminary study of the mode-hopping phenomenon in extended interaction oscillator

The mode-hopping phenomenon in extended interaction oscillator (EIO) based on the multiple-gap topology resonant system is studied to verify the remarkable advantage of the electronic tuning property for EIO. In contrast to the conventional EIO where electron beam interacts with the standing-wave mode in a narrow operating voltage range, the presented EIO can operate in a sequence of neighboring backward-wave modes by switching the beam voltage. According to particle-in-cell (PIC) simulation in CST, the mode-hopping effect has resulted in radiation power fluctuation. Simulation results demonstrate that the EIO is capable of electronic tuning in a relatively wide operating voltage range from 4.1 kV to 9.5 kV. An output power on the order of a few tens of watts is obtained. The study of the mode-hopping effect can show a promising way to operate the EIO in the backward-wave regime.