Particle-in-Cell Simulation of the Impact of High-Energy Secondary Electrons on a Ka-Band TM $_{03}$ Relativistic Backward-Wave Oscillator

This article investigates the influence of high-energy secondary electrons on a Ka-band TM $_{03}$ relativistic backward-wave oscillator (RBWO) using the particle-in-cell (PIC) simulation code UNIPIC. The code incorporates a secondary electron emission (SEE) model suitable for high-incident electron energies. The PIC simulation results show that low-energy secondary electrons have minimal impact on the Ka-band RBWO. In contrast, although the emission yield of high-energy secondary electrons is small, these electrons can return near the cathode, significantly affecting output power and startup time. The insights from this study on the impact of high-energy secondary electrons on RBWO can offer valuable guidance for RBWO design and optimization.